A new strain of mpox (formerly known as monkey pox) has been identified in adults and children on the Democratic Republic of Congo (DRC) border with Rwanda and Burundi. This new cluster of cases appears to be more dangerous than previous outbreaks in a variety of ways such as being spread more easily and causing serious disease, deaths in children and adults. This has prompted concerns within the public health community on the ground and abroad.

Journalists came to hear from those investigating this outbreak on what they know so far about this new strain, what unknowns remain and what action and research is needed to fully understand and respond to this outbreak.

Speakers included:

Leandre Murhula Masirika, Research Coordinator in DRC, The Health Department, South Kivu Provence

John Claude Udahemuka, Lecturer, University of Rwanda

Dr Pacifique Ndishimye, Senior Research Fellow, African Institute for Mathematical Sciences (AIMS) Rwanda

Prof Trudie Lang, Professor of Global Health Research and Director of The Global Health Network, University of Oxford

Dr Freddy Siangoli, Division Provinciale de ca Sante (Provincial Health Division)

A study published in Nature looks at the infectivity and transmission of H5N1 influenza.

Prof Ash Banyard, Virologist, Animal and Plant Health Agency, said:

“The work by Eisfield et al uses well established laboratory models to start to fill some of our gaps in understanding of the potential ability for the newly emerged clade of avian influenza in cattle in the US to transmit to humans.

“The data is robust and both models and approaches used are consistent with earlier studies and support the current thinking that human infection risk from this virus is low.

“This reflects what is being reported from America with only four reported human cases, all of which have been described as having only mild clinical disease with no evidence of onward spread”

Dr Ruth Harvey, Deputy Director of the Worldwide Influenza Centre at the Francis Crick Institute, said:

“Overall, the experimental design for the study is comprehensive, the data has been interpreted well and the authors have reached fair conclusions without speculation. They identify the limitations in that the work was performed on a single strain of the new Bovine influenza virus, and that more work is needed to come to definitive conclusions about the characteristics of Bovine H5N1 influenza.

“There are some novel characteristics of this work compared with other studies, such as demonstrating the ability of the virus to bind to both a2, 3 and a2,6 sialic acid. This is of concern as it suggests a possible increase in the potential of this virus to infect other mammals, including humans, although more research is needed to confirm how this would happen in practice.”

Prof Ian Brown, Group Leader, The Pirbright Institute, said:

“The research provides new information on the possible threat cow flu poses to animal and public health. The study uses models that have been used regularly to assess wider risk including to humans. The results show unconvincing transmissibility within mice (other than to suckling pups from infected mothers) and ferrets but do report systemic infection including of the mammary gland consistent with that seen in cows. The mouse model in particular does not always produce data that can be directly correlated with humans. The work on predicted binding to cells offers new evidence for wider attachment including to cells lining the upper respiratory tract of humans but requires further study to understand the underlying factors. Overall the study findings are not unexpected but this report provides further science insight to an evolving situation, that emphasises the need for strong monitoring and surveillance in affected or exposed populations, both animals and humans to track future risk.”

Dr Ed Hutchinson, Senior Lecturer, MRC-University of Glasgow Centre for Virus Research (MRC CVR), said:

“The ongoing outbreak of H5N1 influenza in American dairy cows was a shock for virologists. It was surprising because cattle were not a known host for this sort of influenza virus. It was also surprising, and alarming, because very large amounts of H5N1 virus are shed into the milk of infected cattle. In some parts of the USA, the remains of H5N1 viruses have been detected in a substantial proportion of the cows’ milk sold to consumers. We normally think of influenza viruses as respiratory viruses (or in birds, viruses of the gut). An influenza virus spreading in milk raises urgent questions, which this important paper from one of the world’s leading influenza research groups does a lot to answer.

“In this paper, the authors used mice and ferrets, two small mammals commonly used to study influenza virus disease in laboratories, to investigate the behaviour of an H5N1 ‘cow flu.’

“First, they returned to a brief experiment they had already published, confirming that H5N1 cow flu in milk can infect animals that consume or inhale that milk. It is very important to note that this risk applies only to unpasteurised ‘raw’ milk – they, and other groups, have already shown that pasteurisation of milk effectively inactivates influenza viruses. However, consuming raw milk in areas affected by the H5N1 outbreak is clearly a very risky thing to do.

“Next, they explained how a virus that entered through the mouth or nose was getting into milk. By comparing infections with cow flu to infections with a highly pathogenic H5N1 bird flu, and with normal seasonal human flu, they found that while the seasonal flu stayed in the respiratory tract, both of the H5N1 viruses spread throughout the bodies of the infected animals. In doing so the viruses invaded multiple organs including the mammary glands. We already knew that one of the things that makes H5N1 influenza viruses so dangerous is their ability to spread beyond the respiratory tract to other organs. Until the virus turned up in an animal we harvested milk from we hadn’t paid much attention to the mammary glands. Now that we’re looking, it seems like spreading into the mammary glands is something that any of these highly pathogenic H5N1 viruses could do. (Seasonal influenza viruses, which generally stay in the respiratory tract, do not do this.)

“Finally, the authors looked at how cow flu is transmitted. Unsurprisingly, they found that infected mouse mothers could pass the virus on to their pups through their milk. Slightly more reassuringly, they found that in ferrets (a model for respiratory transmission), cow flu could not transmit effectively through breathing – in the same experiment, human seasonal flu did spread efficiently. However, there are still some reasons to be concerned here. The Kawaoka group have previously shown that, in principle, H5N1 bird flu viruses can gain the ability to spread through the respiratory route in mammals. In this case, when they compared their cow flu isolate to bird flu they found that it had already begun to gain some of the properties that would be associated with the ability to spread effectively through respiratory infections in humans. To be clear, it does not appear to be doing this yet, and none of the four human cases so far reported have shown signs of onward transmission. However, this new H5N1 influenza virus would be even harder to control, and even more dangerous to humans, if it gained the ability for effective respiratory spread. Although it is good news that cow flu cannot yet do this, these findings reinforce the need for urgent and determined action to closely monitor this outbreak and to try and bring it under control as soon as possible.”

‘Pathogenicity and transmissibility of bovine H5N1 influenza virus’ by Amie J. Eisfeld et al. was published in Nature at 16:00 UK Time on Monday 08 July 2024.

DOI: 10.1038/s41586-024-07766-6

Declared interests

Dr Ed Hutchinson:  Ed Hutchinson is a Senior Lecturer at the MRC-University of Glasgow Centre for Virus Research (CVR). He was not involved in the current study, though he was involved in one of the other studies showing that pasteurisation of milk effectively inactivated influenza viruses. He has received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). He has unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical.

Prof Ian Brown: I lead an UK research consortia that are addressing some (not all) similar questions but with different early results on receptor binding.

Dr Ed Hutchinson: Ed Hutchinson is a Senior Lecturer at the MRC-University of Glasgow Centre for Virus Research (CVR). He was not involved in the current study, though he was involved in one of the other studies showing that pasteurisation of milk effectively inactivated influenza viruses. He has received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). He has unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical.

Scientists comment on cases of the Oropouche virus in South America and Europe. 

Dr Philip Veal, Travel Health Consultant at UKHSA, said:

“The midge that carries Oropouche virus is not currently established in Europe.  It is typically found in the Americas.  There is no evidence that the virus can spread from person to person.

“When travelling to affected areas, you can avoid the infection, and others such as dengue, Zika and malaria, by preventing insect bites.  Use insect repellent, cover exposed skin and sleep under a treated bed net.  Plan ahead and visit the TravelHealthPro website to look up your destination and the latest health information and advice, particularly if you are pregnant.”

Background

• More info here: https://travelhealthpro.org.uk/news/788/oropouche-virus-disease-information-for-travellers-and-health-professionals
• All of the cases diagnosed in Europe were acquired elsewhere
• In July 2024, the Brazil Ministry of Health reported six possible cases of OROV being passed from mother-to-child during pregnancy (vertical transmission).

Dr Benjamin Brennan, Senior Research Fellow, MRC-University of Glasgow Centre for Virus Research, said:

“The Oropouche virus is endemic in parts of South America and has been for some time.  It is in the news now because there has been a large and sustained outbreak of Oropuche fever in several South American countries (approx. 8000 cases) associated with the emergence of a novel Oropouche virus that has arisen due to a reassortment event.  What is unusual in this outbreak is the first reports of death following infection with this virus in South America and the observation that the virus may be being passed from mother to child in utero and result in miscarriage, abortion and/or developmental problems, and deformities of the foetus.

“The virus is transmitted to people through the bite of an infected Culicoides paraensis midge, which exists in South America (and not in Europe).  Oropouche virus has not been demonstrated to be transmitted directly between humans.

“The virus causes a disease with typically mild symptoms, that people recover from after 1-2 weeks and is rarely fatal.  In humans, Oropouche disease can manifest as an acute febrile illness with headache, nausea, vomiting, muscle and joint pains, and occasionally more severe symptoms (e.g. neurological symptoms and meningitis).  The prognosis for recovery is good and fatal outcomes are extremely rare.  However, there are recent reports in South America of Oropouche virus being transmitted from infected pregnant women to developing foetuses.  The impact of Oropouche infection for pregnant women, foetuses and newborns may therefore be higher than that for the rest of the public.  Pregnant women planning to travel to epidemic countries where transmission is ongoing (i.e. Cuba, Brazil) or has been reported should always seek pre-travel health advice to assess the risk of infection based on the local situation.

“Given the relatively high number of travellers between Europe and affected countries such as Brazil or Cuba, it is likely we will continue to see sporadic cases of Oropouche fever in returning travellers in Europe.  Nineteen cases have been reported so far, in Spain, Italy and Germany.  In these incidences most travellers had returned from Cuba.  We may see cases in the UK in returning travellers that have visited or reside in an epidemic area.

“Currently there are no vaccines or specific medicines to treat Oropouche fever.  Therefore, the best way to prevent an ongoing outbreak would be to follow any instructions given by local public health authorities in the affected country and to use personal protective measures to reduce midge and mosquito bites both when undertaking outdoor activities or inside houses that are not adequately screened.  The midge species that transmits the virus in South America bites during the day and readily enters houses, with peaks in activity after sunrise and before sunset.”

Prof Stephen Graham, School of Biological Sciences Infection and Immunity Theme Leader and Professor of Virus:Host Interactions, University of Cambridge, said:

What is this virus, has it been around for a long time in South America?

“The virus was first discovered in Trinidad and Tobago in 1955, on the Oropouche river (hence the name).  It has been circulating in Latin America and the Caribbean since then, with sporadic outbreaks in countries such as Brazil and Peru.  Up until the Zika outbreak in 2016 it was the second most prevalent insect-transmitted virus in Brazil, after Dengue virus.  This latest outbreak is notable because the virus has spread much further geographically than it has in previous outbreaks, as far north as Cuba and as far south as Sao Paulo state.  There have also been cases imported by travellers into Spain, Italy and Florida.

“The virus has an RNA genome, like SARS-CoV-2, which means that it is capable or rapid mutation.  It also has a genome with multiple segments, like influenza.  This means that if you are unlucky enough to be infected with two different strains of the virus they can ‘reassort’ their genome segments, like shuffling two decks of cards together, and you might end up with a new virus strain that is more transmissible and/or more pathogenic.  This is what appears to have happened recently in Brazil to launch the current outbreak.  It’s important to note that individual humans or animals being infected by two different strains at the same time is a very rare event.  In this case the most likely scenario is that the co-infection and reassortment occurred in a wild animal (sloth, monkey or other), probably some years ago, and was then subsequently transmitted to a human via a biting insect.

How is the virus transmitted?

“The virus is transmitted via biting insects – the main transmission vector is thought to be the midge Culicoides paraensis.  It is possible that it can be transmitted by other types of midges and mosquitos – but for that to be a problem you’d also need to first have the virus present endemically in a country (which isn’t the case in Europe).  The ECDC have said that there is no evidence that the insects we have in the UK or mainland Europe are capable of transmitting Oropouche virus, although we are working with somewhat sparse data on this.  There are currently no known examples of ‘secondary transmission’ of the virus outside endemic areas so I concur with the ECDC that the risk of local transmission in Europe is low.

Is there anything unusual about the current outbreak in South America?

“As mentioned above, the above outbreak is unusual in its broad geographic spread.  It’s also very unusual in the fact that we have observed the first recorded cases of mortality from Oropouche virus infection – two women in their 30s with no known co-infections or other serious disease.  This marks quite a change in the virus as it has always made people very sick, with debilitating fever and muscle pain for about 1-2 weeks, and occasionally neuronal symptoms like meningitis, but it has never before killed people.  Additionally, there have been anecdotal reports since the 1980s that Oropouche virus infection of women in the first trimester of pregnancy could cause foetal death.  We have unfortunately now seen several cases of early-term abortions where the foetus was infected with Oropouche virus.  This has potential public health implications so we need to maintain vigilance and monitor the situation carefully.

Is it normal for us to see some imported cases outside South America in returning travellers?

“In short yes, this is a virus that infects people and people travel.  If you visit an area where there is an epidemic and are bitten by an insect carrying Oropouche you might not develop symptoms for 2-3 days, and by that time you might have flown home to Europe or the USA.  However, we have no evidence that the virus can spread directly from person to person – you need an insect to bite you and then bite someone else to transmit the disease – and there’s no evidence that the insects we have in the UK or on mainland Europe are able to transmit Oropouche virus infection.  We also don’t have any evidence that the virus can infect other animals in the UK, whereas in Brazil it is thought to circulate in the local sloth and monkey populations.  The good news is that cases in the Amazon region are starting to drop.  However, there is a lot we don’t know about this virus still so we can’t completely rule out that the virus will continue to spread more widely in Brazil or Latin America during the current outbreak, especially given the continuing climate and land use changes in areas where the virus circulates like the Amazon.  As the climate warms the insects that spread the virus will change their geographical distribution, potentially introducing new human and animal populations to the infection – and as more people live in close proximity to the Amazon you have more potential for spread from wild animals to human hosts.  Again, the good news here is that most people recover completely from Oropouche virus infection within a few weeks, so this virus won’t cause a SARS-CoV-2 like global pandemic.”

Prof Jonathan Ball, Deputy Director of Liverpool School of Tropical Medicine and Professor of Molecular Virology, Liverpool School of Tropical Medicine (LSTM), said:

“There is no evidence of direct human-to-human infection, the infection is acquired from an insect bite in an area where the virus is endemic, often from a tick, but sometimes a mosquito that lives in South America.

“The symptoms are akin to those seen with Dengue fever, varying from relatively mild, often asymptomatic to much more painful aching and fever.  There have been reported possible cases of serious disease in newborn children in South America presumably arising from infection in the womb, and possibly still-births, but this isn’t proven to be associated with Oropouche infection.

“There are no vaccines or specific treatments, so the only way to reduce outbreaks is limit exposure to insects in infected areas (i.e. South America) and also use insect controls.  Eventually, as people become naturally immune following infection then the size of the susceptible population declines so the outbreak declines.

“For anyone travelling from an area where the virus isn’t normally found (so-called non-endemic areas) to an area where the virus is circulating – in this case South America – there is the risk of them becoming infected.  This risk increases as the number of active cases increases, so during an outbreak, as we are seeing in Brazil, then there is a greater chance of becoming infected, but the absolute risk is still low, especially if the traveller protects themselves from insect bites, and especially tick bites.  The fact that CDC have travel to the Americas as level 1 risk – ‘Practice usual precautions’ – highlights this relatively low risk.  We could see isolated cases in the UK, but these would be in travellers returning from an outbreak area.  The risk of subsequent onward transmission within the UK is very unlikely.”

Dr Enny Paixao, Associate Professor, London School of Hygiene & Tropical Medicine, said:

Commenting on the Oropouche outbreak across South America:

“There is much we still do not know about the Oropouche virus but one of the main concerns arising from the current outbreak in South America is its potential harmful effects on unborn foetuses.

“In July 2024, the Pan American Health Organization (PAHO) issued an alert regarding the potential transmission of the Oropouche virus from mother to child in Brazil.  Some very limited studies have suggested that antibodies against the virus have been found in children born with microencephaly and that there may be a link between infection, miscarriage, and foetal deaths in Brazil, but further research is needed to investigate a potential causal link.

“While the current Oropouche outbreak in South America does not yet show the same level of abnormalities in newborns as the Zika epidemic, the risks to foetal development remain uncertain and require closer scrutiny.

“Several factors may explain the recent outbreak, including enhanced surveillance, climate and environmental changes, and potential changes to the virus.

“Similarly to other vector-borne diseases such as dengue, climate change may also be impacting Oropouche virus expansion.  Changes to temperature and precipitation can affect transmission, for example, rising temperatures can enhance the rate of development of Culicoides midges, one of the virus’ main transmission vectors in South America alongside mosquitos.

“Previous studies have linked OROV outbreaks to increased agricultural activities, highway and road development and bridge construction in South America.  These activities disrupt ecosystems by causing population migration, vegetation loss (such as deforestation and illegal mining) and changes in agricultural practices.  These changes can alter the distribution of wild animal reservoirs and vectors.

“A recent study also indicates that the main Oropouche virus circulating in South America in 2023-2024 exhibits significantly higher replication in mammalian cells compared to older strains.  While it remains unclear if this increased replication leads to greater transmissibility by its vectors, it could help explain the recent rise in cases.

“Surveillance for Oropouche infection is challenging, as there is overlap of symptoms with other co-circulating arboviruses like dengue, Zika and chikungunya.  It’s also important to note that the reported figures are based on laboratory-confirmed cases and taking into account that some individuals will not experience symptoms or seek health care, it’s likely that the true number of infections is higher.

“Therefore, it is plausible that the increased number of cases and enhanced surveillance are bringing rare events, including deaths, to light.  The same principle applies to the potential harmful effects on unborn children.

“Although Oropouche virus is not new to Brazil, the factors driving the recent sharp increase—including reported deaths and potential foetal harm—highlight the need for further investigation.  Until advancements are made in vaccine development or mosquito and midge control, or until natural immunity within the population in Brazil increases, the challenge posed by this neglected tropical disease will persist.”

Declared interests

Dr Benjamin Brennan: “I have no conflicts of interest to declare.”

Prof Stephen Graham: “I hold an International Collaboration Award research grant from the Royal Society to study Oropouche virus, together with my colleague Eurico Arruda at the University of Sao Paulo.  We are working to develop rapid testing (lateral flow devices) to diagnose Oropouche virus infection at community points of care in the Amazon.”

For all other experts, no reply to our request for DOIs was received.

Scientists react to the WHO declaring Mpox a Public Health Emergency of International Concern. 

Dr Brian Ferguson, Associate Professor of Immunology, University of Cambridge, said:

“The WHO has declared a PHEIC due to the continued spread of monkeypox virus in multiple African countries. The DRC has reported a large increase in cases of Mpox, nearly 8000 in 2024 alone. Cases have also now been found in countries that have not reported Mpox previously; Burundi, Kenya, Rwanda and Uganda. It is thought that the majority of these cases are of caused by clade 1b monkeypox virus, which is more virulent than the clade 2 virus that caused the global outbreak in 2022.  These three factors are the main drivers behind the WHO’s decision to declare a PHEIC. This is timely and sensible as co-ordinated, multinational efforts are required to stop the further spread of the virus and to stop history repeating only two years later.

“The situation is concerning because of the spread of the clade 1b virus, which is considered to cause more severe disease, and because there are many children being infected in DRC during this new outbreak. 40% of cases are in children under 5 years old. As mpox disease is more severe in immunocompromised individuals, it is also a concern that the current outbreak is taking place in a region where HIV prevalence is relatively high but access to antiretroviral drugs is poor. There is further concern about the lack of access to vaccines and a globally slow response to vaccine production and distribution. Even though there are existing effective vaccines, there are not enough doses and they are not being getting to where they are needed. The WHO is attempting to address these issues, but this requires greater international effort to produce and deliver vaccines. Equally urgent is the need for increased surveillance, including molecular epidemiology, and better diagnostics to provide clearer information about the transmission and virulence, particularly of the clade 1b virus.”

Dr Jonas Albarnaz, a Research Fellow specialising in pox viruses at The Pirbright Institute, said:

“A concern is that clade 1 monkeypox virus is associated with a more severe disease and higher mortality rates than the clade 2 virus responsible for the international mpox outbreak in 2022. An outbreak of clade 1 virus is ongoing in DRC since 2023, with thousands of cases suggesting that there’s sustained human-to-human transmission. A significant number of cases among children has been reported in this outbreak as well. Clade 1 monkeypox virus is known for causing more severe disease in young children, pregnant women, and immunocompromised people. The emergence of the new clade 1b variant changed this picture as cases have been reported outside DRC (Burundi, Kenya, Rwanda). Most of the clade 1b has been in young adults, and sexual networks seem to be driving its spread. However, there is no evidence that this variant transmits better or causes a more severe disease than clade 1a. This may change as we learn more about this new variant.

 “There are multiple outbreaks happening at present:

1. Clade 1 MPXV outbreak in DRC, going on since 2023; the number of cases this year has already surpassed last year’s numbers (>14k).
2. Clade 1b MPXV outbreak in DRC, with confirmed cases in Burundi, Kenya, Rwanda.
3. Clade 2 outbreak in South Africa, mostly among people living with HIV; clade 2 was responsible for the international mpox outbreak in 2022 that subsided now in Western countries.

“This coordinated effort to contain MPXV spread in Africa is welcome and may prevent what happened in 2022 from happening again. There was an ongoing clade 2 MPXV outbreak in Nigeria since 2017 with evidence of sustained human-to-human transmission, but this situation only caught global attention when it spread to Western countries and caused the international outbreak in 2022.

 “Two main challenges remain:

1. Little is known about the natural history and transmission dynamics of the new clade 1b variant, and this information is key to inform the control strategies.
2. Vaccines exist but their availability is very limited; this represents a major bottleneck for the control strategies.”

Prof Jimmy Whitworth, Emeritus professor London School of Hygiene and Tropical Medicine, said:

“The current epidemic of Clade 1b mpox in eastern Democratic Republic of Congo and neighbouring countries is very concerning, and it is to be welcomed that Africa Centres for Disease Control (Africa CDC) and the World Health Organization have declared this to be a public health emergency. These declarations amount to a call for action, and should lead to the prompt mobilization of money and resources, and a co-ordinated international response to the epidemic. The epicentre of the epidemic in South Kivu is undergoing a protracted humanitarian crisis and getting the necessary facilities in place for surveillance, diagnostic testing, contact tracing and case management, is going to be very challenging. The amount of vaccine required has been estimated by Africa CDC  to be 10 million doses. The cost and availability of vaccine is going to be a great challenge, but it is really important that, unlike in the COVID-19 pandemic, there is global solidarity, that the vaccine reaches the people who need it most and that it is not stockpiled by rich countries. This is a real challenge for the global health security community to demonstrate that they can work together for global public good and not for narrow national interests. Let us hope they take that opportunity, otherwise we risk this epidemic spreading across the African continent, and possibly beyond.”

Prof Trudie Lang, Professor of Global Health Research and Director of The Global Health Network, University of Oxford, said:

“The local health research teams working to tackle mpox in Africa will be pleased with this important and timely decision from WHO.

“There are currently two variants of mpox circulating in Africa. Clade 1 and Clade 1b. Clade 1b has recently emerged and there are many unknowns that need to be addressed.

“Teams are working rapidly, in highly challenging settings in partnership with international organisations to gather this vital data. There is emerging evidence of differences in transmission and symptoms; such as more commonly passed person to person and from mothers to their babies in pregnancy. It can be a very dangerous infection and there have been deaths, but to understand the mortality rate we need to understand better the number who are infected overall, including those with milder disease and how infected they are? We need to also understand better the relationship between transmission route and severity of disease. This disease impacts highly vulnerable communities and there is already much stigma associated with this. Therefore, we need to understand people’s perceptions and practices to enable effective public health interventions and messages to encourage treatment seeking and guide safer practices to reduce risk of infection.

“Indeed, the most important reason this decision will be welcomed and supported is because the most immediate and vital requirement is community level education and awareness so those most vulnerable can be guided to reduce their risk and supported to seek treatment.

“Vaccines are imperative and the existing, as well as those in development, and need to be tested in the regions where Clade 1b is  escalating to assess if they work in this variant and to get traction in preventing further spread to further new regions both in Africa and globally.”

Dr Boghuma Titanji Assistant Professor of Medicine, Department of Medicine at Emory University, said:

“A Public Health Emergency of International Concern (PHEIC) is a critical designation by the WHO, marking an ‘extraordinary event’ that poses a substantial threat to global health through the spread of disease across borders. This designation is reserved for situations that are ‘serious, sudden, unusual, or unexpected,’ with far-reaching public health implications beyond the affected nation. Declaring a PHEIC signals the urgent need for a coordinated international response and immediate global action.

“The WHO’s recognition of the current mpox outbreak as a PHEIC, in tandem with Africa-CDC’s declaration of a continental emergency, underscores the gravity of the crisis. This pivotal step highlights the critical funding gaps that must be addressed to ensure that the declaration leads to the necessary resources for controlling and ultimately ending the outbreak.

“This decision is a stark reminder to the global community of the vital importance of early intervention when infectious diseases are still geographically contained. However, previous PHEIC declarations have exposed the shortcomings of the current framework in managing crises that demand a sustained, multi-tiered response. While a PHEIC is instrumental in mobilizing international coordination, securing funding, and expediting the development of vaccines, treatments, and diagnostics, these efforts must be matched by continuous support. In the case of mpox, it is crucial that this translates into resources for testing and surveillance, vaccines and therapeutics, as well as much-needed funding for research to understand the dynamics of this outbreak.

“The essence of a PHEIC declaration is to catalyze prompt, evidence-based actions that mitigate the impact on public health and society, while avoiding unnecessary disruptions to travel, trade, or the marginalization of affected communities. To succeed, the global health community must view this declaration not just as an urgent call to action but as a commitment to a sustained, coordinated effort that can prevent the ongoing mpox outbreak—and future threats—from escalating into full-scale global emergencies.”

Dr Josie Golding, Head of Epidemics & Epidemiology in Wellcome’s Infectious Disease team, said:

“Epidemics pose a threat to health and health equity globally. Mpox has affected West and Central African communities for decades, only gaining global attention during the 2022 outbreak in Europe and North America. The current surge of cases in Africa demonstrates the ongoing and growing threat of Mpox. The WHO declaration of a PHEIC and Africa CDC announcement on Tuesday are a strong signal for those across the continent and worldwide to join forces and coordinate efforts to control this virus. We should not wait for diseases to escalate and cross borders before acting. Effective outbreak control requires sustained, coordinated efforts worldwide – from local and national governments, and public and private industry to funders, regulators and NGOs.”

https://www.who.int/news/item/14-08-2024-who-director-general-declares-mpox-outbreak-a-public-health-emergency-of-international-concern#:~:text=In%20July%202022%2C%20the%20multi,sustained%20decline%20in%20global%20cases.

Declared interests

Dr Brian Ferguson: No declarations of interest

 Dr Jonas Albarnaz: I was part of the UKRI Mpox Research Consortium (led by Geoff Smith and Bryan Charleston), but this funding has ended.

Prof Jimmy Whitworth: No interests to declare.

Prof Trudie Lang: No conflict of interest

No others received

Scientists comment on reports of a case of Clade 1 Mpox in Sweden.

Dr Jonas Albarnaz, a Research Fellow specialising in pox viruses at The Pirbright Institute, said:

“There are diagnostic PCR tests that can differentiate between clade 1 and clade 2 mpox virus based on genetic differences between these two virus strains. So far, sequencing of the virus genome has been used to confirm clade 1b cases in Africa. However, the availability of these new clade 1b genomes will allow the development of diagnostic PCR tests to differentiate between clade 1 and clade 1b as well.

“This news of a case of Clade 1 mpox in Sweden is concerning for two main reasons. First, this is the first clade 1 mpox virus case outside Africa. This indicates that the extent of the international spread of clade 1 outbreak in DRC might be larger than we knew yesterday. And second, clade 1 mpox virus is associated with a more severe disease and higher mortality rates than the clade 2 virus responsible for the international mpox outbreak in 2022.

“This is hard to predict whether we will see further cases of Clade 1 mpox outside of Africa, but this case in Sweden is a warning call for public health authorities to be vigilant and implement robust surveillance and contact-tracing strategies to detect possible new cases early on. It’s also critical to determine what is the link between this clade 1 monkeypox virus detected in Sweden and the ongoing outbreak in DRC.”

Some background on previous mpox cases and outbreaks outside of Africa:

“The 2003 outbreak in the USA was associated with prairie dogs infected with clade 2 that had been imported from Africa. Prior to the 2022 international outbreak of clade 2, a few clade 2 cases were reported outside Africa but they were imported from endemic countries in Africa.”

Dr Brian Ferguson, Associate Professor of Immunology, University of Cambridge, said:

“The appearance of a case mpox disease caused by clade 1 mpox virus in Sweden is clearly a concerning development. It is not surprising, given the severity and spread of the outbreak in Africa, that travel between continents has brought this case to Europe. There will likely be more here and in and other parts of the world as there are currently no mechanisms in place to stop imported cases of mpox happening. The timing of this case comes less than 24 hours after the WHO’s PHEIC declaration and only 15 months after the WHO ended the previous mpox PHEIC in May 2023. The lack of activity in the intervening period has resulted in what could now become a new global outbreak. There should have been a greater effort to produce and distribute vaccines to the affected areas, but this has not happened. It is possible to address these problems but this requires rapid international co-operation.” 

Prof Francois Balloux, Professor of Computational Systems Biology and Director, UCL Genetics Institute, UCL, said:

“The recent case of mpox detected in Sweden was likely diagnosed as clade I through whole genome sequencing. Whether the case belonged to the I or Ib lineage has not been released so far. The person who has been diagnosed in Sweden has been infected during a stay in a part of Africa where mpox is endemic. As such, there is no evidence for transmission in Europe at this stage. Given the sizeable number of recent mpox clade I cases in parts of Africa, it is not surprising that a case has been diagnosed in a European country. At this stage, Sweden is not taking additional measures beyond those already in place. It is to be expected that other imported cases of mpox clade I will be identified outside Africa over the coming months.”

https://www.folkhalsomyndigheten.se/the-public-health-agency-of-sweden/communicable-disease-control/disease-information-about-mpox/one-case-of-mpox-clade-i-reported-in-sweden/

Declared interests

Dr Jonas Albarnaz: I was part of the UKRI Mpox Research Consortium (led by Geoff Smith and Bryan Charleston), but this funding has ended.

Dr Brian Ferguson: No conflict of interests to declare.

Scientists comment on UKHSA announcing that the UK has secured doses of the human H5 influenza vaccine. 

Dr Ed Hutchinson, Senior Lecturer, MRC-University of Glasgow Centre for Virus Research (MRC CVR), said:

“Although at the moment there’s no evidence of H5N1 spreading among humans in the UK the growing concern about the outbreak in cattle in the US means it’s sensible to take precautions.

“In the event they were needed, initial doses would not be for the whole population but may be valuable for key groups such as healthcare workers or farm workers. 

“We know from recent data in the US that H5 vaccines continue to provide protection even as the virus evolves so this would be a valuable thing to acquire in advance.”

Dr David J Allen, Associate Professor in Virology at University of Surrey, said:

“H5 influenza is a subtype of the influenza virus that usually infects birds and is sometimes referred to as highly pathogenic avian influenza (HPAI). In 2020, a new type of the H5 influenza virus, (clade 2.3.4.4b) spread via migratory birds to parts of Africa, Asia and Europe, reaching North America in 2021 and South America in 2022. Most of the H5 influenza viruses detected and characterised since 2020 belong to clade 2.3.4.4b.

“Whilst H5 influenza viruses mainly infect birds, on rare occasions these viruses can infect humans. H5 influenza infections in humans can cause severe disease and can be fatal. Since 2021, 35 cases of H5 influenza in humans have been reported, at least 17 of which were associated with the emerging clade 2.3.4.4b viruses.

“Influenza viruses from birds and mammals can adapt to infect humans leading to pandemic events, for example as happened in 2009. Continued surveillance of circulating influenza viruses is crucial to understand the emergence of these viruses and the risk they pose to bird, animal and human populations.

“Having a robust preparedness plan in place is important make sure the UK is ready to respond to any change in the cases of influenza, including H5 subtypes, as acting quickly will be crucial to getting any influenza outbreak under control. There are many important parts to preparedness for influenza outbreaks and ensuring there is an available stock of the H5 influenza vaccine is a key measure to make sure at-risk individuals can be protected quickly in the event of an outbreak.”

Prof Ian Brown, Group Leader, The Pirbright Institute, said:

“The current global panzootic with H5 high pathogenicity avian influenza viruses in birds and animals is presenting on such scale that the risk to humans has increased. There are occasional spill over events to humans,  principally to those who been occupationally exposed to infected birds and animals, with most human infections being mild. The H5 viruses presently lack the properties to efficiently infect the upper respiratory tract of humans and transmit between. However, a vaccine stockpile is an important preparedness step should H5 viruses mutate and expand their capability to infect and transmit between humans. If this scenario were to occur vaccine stockpiles would have an important role in the early control of substantially increased risk or a pandemic.”

Prof Sir Andrew Pollard, Director of the Oxford Vaccine Group, University of Oxford, said:

“Emergence of a new strain of influenza remains at the top of the list of pandemic threats and so providing resilience against potential risky flu types, like H5, is important for future pandemic and outbreak preparedness. H5 is only one of the multiple families of flu viruses that create such a risk, so we should not be complacent. But H5 is the one that we are most concerned about today as a result of the global spread of this virus amongst birds and various mammals, and worryingly across the United States amongst cattle this year. H5 is out there and we need to do all we can to be prepared.”

Prof Massimo Palmarini, Director of the MRC-University of Glasgow Centre for Virus Research (CVR), said:

““H5 is spreading globally in birds (and has spilled over in a variety of mammalian species in some countries) so it is prudent that we get ready and prepare for what might happen in future — it might be that we never need it but it seems like a sensible thing to do to be prepared.”

UKHSA press release – UK secures H5 influenza vaccine to boost pandemic preparedness:

https://ukhsa-newsroom.prgloo.com/news/uk-secures-h5-influenza-vaccine-to-boost-pandemic-preparedness

Declared interests

Dr Ed Hutchinson: I started working on the molecular biology of influenza viruses as a graduate student with Paul Digard at the University of Cambridge. In 2009 I moved to the University of Oxford to work on influenza with Ervin Fodor, as a postdoctoral researcher at the Sir William Dunn School of Pathology and a Junior Research Fellow at Worcester College (2010-2014), and in 2016 I set up a research group at the MRC-University of Glasgow Centre for Virus Research.

He has received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). He has unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical.

https://www.gla.ac.uk/schools/infectionimmunity/staff/edwardhutchinson/#

Dr David J Allen: I have previously worked for the predecessor organisations of UKHSA (i.e. Health Protection Agency and Public Health England) between 2009-2017.

Prof Ian Brown: I am a PI on UK research grants with a focus on avian influenza in birds. I do not receive funding myself directly from industry or pharma but am involved in international programmes to track and match circulating viruses in birds with vaccines being used in those sectors only. I am a member of the UK scientific committee ‘New and Emerging Respiratory Threats Assessment Group’ and participate in UKHSA led fora that assess the risk to human health from avian influenza viruses.

Prof Sir Andrew Pollard: Professor Pollard is chair of JCVI which provides independent scientific advice on vaccines to DHSC. The comment above is given as Director of the Oxford Vaccine Group, not as JCVI chair.

Prof Massimo Palmarini: MP is a member of the Standing Committee on Pandemic Preparedness of the Scottish Government.

A study published in Science looks at a mutation in bovine influenza (H5N1) hemagglutinin (HA) which could switch binding specificity to human receptors. 

Prof Ian Brown, Dr Thomas Peacock and Prof Munir Iqbal, Influenza Research Leads at The Pirbright Institute, said:

“This new study reaffirms the importance of closely tracking and monitoring H5 viruses that can transmit between animal populations to look for changes that might alter their binding affinities from avian to human cells. The study builds on existing knowledge but in the context of the virus from dairy cattle where key mutations were introduced into a ‘wild type’ virus detected in a single human case. The mutated ‘laboratory’ non infectious viral protein carrying single or double amino acid changes at key sites in the haemagglutinin viral glycoprotein, switched host cell binding from avian to human. It must be stressed that the introduced mutations have not been detected to date in the H5 virus as it naturally transmits between cattle and spills over to avian and mammalian hosts, underlining the importance of work in both UK and overseas research groups that is actively addressing naturally occurring mutations in the virus. As the authors acknowledge the switch in binding preference is one of several barriers the virus must overcome before it can acquire strong affinity to infect humans and spread between.”

Prof Ed Hutchinson, Professor of Molecular and Cellular Virology, Medical Research Council-University of Glasgow Centre for Virus Research, said:

“Over the last year, the highly pathogenic H5N1 ‘bird flu’ influenza virus has gained the ability to infect cattle and has spread widely among dairy herds in the USA. This has provided far more opportunities for the virus to ‘spillover’ and infect humans. These spillover infections of H5N1 can have unpredictable effects. Many have been mild, but some have been associated with severe disease. Importantly, so far H5N1 infections have caused isolated cases, and the virus has not gained the ability to spread efficiently from human to human and create a pandemic.

“There are multiple barriers to H5N1 adapting to spread efficiently among humans. The most important is probably the ability of the virus to bind to new cells by grabbing onto sugars on the cell surface with ‘spikes’ of a protein called HA. These sugars are different shapes in different animals. Birds make different sugars from humans. The sugars in cows look more bird-like than human-like, which means that an influenza virus adapted to birds (or cows) would have to evolve and change the way HA binds to sugars to spread efficiently among humans.

“In this paper, the authors (leading experts in studying the structure of the HA protein) show that just a single mutation in an HA from an H5N1 influenza, isolated from a human case of cow flu, can be sufficient to change it so that it binds to the sugars needed to enter human cells.

“This finding is important because it shows that, in principle, a single mutation might be enough for an H5N1 virus to become better at spreading effectively among humans. This is concerning because influenza viruses can acquire mutations and evolve very rapidly. For example, recent studies of the influenza viruses in a Canadian teenager, who has been severely ill for a prolonged period with H5N1 bird flu, implied that the virus had begun to evolve to ‘explore’ ways of binding more effectively to the cells in their body during the course of an infection. As yet, H5N1 viruses with these changes are not circulating. However, the current study shows that it is in principle possible for H5N1 to take a simple step to evolve into a form more suitable to spread among humans.

“It is very important to note that this mutation is not the only barrier to emergence. As the authors note the virus needs to overcome multiple barriers to become an effective disease of humans, including changing other properties of the HA protein that are needed for aerosol transmission. We do not yet know whether H5N1 influenza viruses will evolve to become a disease of humans. This study only worked only with purified proteins and did not generate any potentially dangerous viruses, so we also do not know for sure if this mutation has any hidden costs for the virus which might make it harder to acquire. However, the work does identify one way in which H5N1 has the potential to become more dangerous for us. It highlights the need for the current outbreak in cattle in the USA to be taken extremely seriously and for every effort to be made to monitor the evolution of this virus and intervene where possible to limit its opportunities to try out its options of evolving further in humans.”

Professor David Heymann at the London School of Hygiene & Tropical Medicine (LSHTM) said: 

“It is always important to look for genetic changes that could indicate a possible increase in transmissibility or virulence, as has been done here by the authors. However, even when a mutation is found, it is still impossible to predict how this may change the behaviour of the organism in humans.

“In addition to surveillance of the virus for emerging mutations, there must be concurrent surveillance to detect cases and continued study of the epidemiology of these infections, the patterns in which they occur and why. This combination is vital to fully understand the behaviour of the virus.

“By understanding the natural history of these infections and making sure that, when confirmed infection occurs, there is an investigation of contacts and others who are in the community, we can begin to piece together helpful characteristics such as asymptomatic cases, and risk factors of infection, including where and how they occur. It’s this broad understanding of a virus that will then help determine the best possible control activities and management of those infected.

“While any new mutations or transmission of a virus can be concerning, it’s important to remember that it also increases our understanding of it, which in turn improves surveillance and vaccine development.”

Prof Tom Solomon FMedSci, Director of The Pandemic Institute, Liverpool, said:

“This is a really important paper. Avian flu has been around for nearly two decades now, and recently spread from birds into cattle in the USA. When humans do occasionally become infected by the virus it is not able to then pass easily from human to human. It does not have the right protein on its surface (called the haemagglutinin protein) to easily infect human lungs. However, this new paper shows which genetic changes would be necessary to alter this protein making human infection more likely. It also shows the protein structure which allows it to interact with human tissue and cause human infections. The scientific community will continue to monitor changes in the virus’ genetics as it evolves further to help us prepare for any future pandemics.”

‘A single mutation in bovine influenza H5N1 hemagglutinin switches specificity to human receptors’ by Ting-Hui Lin et al. was published in Science at 19:00 UK time on Thursday 5 December. 

DOI: 10.1126/science.adt0180

Declared interests

Prof Ian Brown, Dr Thomas Peacock and Prof Munir Iqbal: IB, TP and MI all receive research funding to study avian influenza in multiple hosts. IB is a member of the UK scientific committee ‘New and Emerging Respiratory Threats Assessment Group’. IB and TP  participate in UKHSA led fora that assess the risk to human health from avian influenza viruses. MI receives industry funding for vaccinology and diagnostics.

Ed Hutchinson: He Professor of Molecular and Cellular Virology at the MRC-University of Glasgow Centre for Virus Research. He has received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). He has unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical. Work in his group is funded by the UK Medical Research Council and by Flu-TrailMAP-OneHealth, an H5N1 rapid response consortium. He was not involved in the current study.

Prof Tom Solomon: TS is Director of The Pandemic Institute which has received funding from CSL Seqirus, and AstraZeneca

For all other experts, no reply to our request for DOIs was received.

Scientists comment on an unknown illness in the Democratic Republic of Congo (DRC). 

Prof Paul Hunter, Professor in Medicine, UEA, said:

“We still know very little about this other than so far there have been 376 people reported as affected and 79 dead, however given the difficulties in identifying mild infections in Central Africa, the infection likely has a much lower mortality rate than these figures would suggest.  The illness appears to be predominantly a respiratory infection with symptoms including fever, headache, nasal congestion, cough, difficulty breathing, and anaemia.

“The big question is what is likely to be causing this and that I don’t know for certain.  The mention of anaemia makes me think of Mycoplasma pneumonia but it is too early to make a definite diagnosis until further analyses are reported.

“Reports of outbreaks with fatalities crop up somewhere in the world several times a year.  Almost all turn out to be an already well-known infection with limited global consequences.  But of course, we need to have more information before being able to judge the wider consequences if any of this outbreak.  It is vital that these cases are investigated promptly so that appropriate treatment and control measures can be implemented.”

Dr Jake Dunning, Senior Research Fellow and Consultant in Infectious Diseases, Pandemic Sciences Institute, University of Oxford, said:

“I’d say there are multiple, potential infectious causes for this unidentified illness cluster, based on the symptoms described and descriptions of who is being affected the most, and there are some possible non-infectious causes too.  Speculating about causes for unidentified illness events – which happen periodically, especially in African countries – is not helpful and can sometimes be harmful.  I think we must have faith in officials from the DRC and from supporting agencies, such as the WHO, who are investigating what is a concerning illness cluster (not knowing why people are getting sick or dying is always of concern and worthy of investigation).  We should allow them to do what they say they are doing – case investigations, field epidemiology and laboratory testing to look for potential causes (and if they request assistance, provide it).  Calling this incident a ‘disease X’ outbreak at this point is simply wrong and counterproductive.”

Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:

“At time of writing, there is a huge amount of uncertainty about this outbreak.

“Outbreaks like this will happen many times around the world.  Typically, they are brought under control without spreading too widely, and we may or may not ever find out the exact bug that caused the infections.

“This rural area in the DRC also means the public health response is more complicated.  However, the country has had mpox and Ebola outbreaks in recent, so they are experienced at addressing infectious disease epidemics.”

Declared interests

Prof Paul Hunter: “No conflicts.”

Dr Jake Dunning: “Nil to declare.”

Dr Michael Head: “No COIs.”

Scientists comment on cases of Human Metapneumovirus (hMPV) reported in China. 

Prof Antonia Ho, Professor and Hononary Consultant of Infectious Diseases, Medical Research Council-University of Glasgow Centre for Virus Research, said:

“Human metapneumovirus (hMPV) is a respiratory virus that predominantly causes mild flu-like illness, though can cause severe disease, such as bronchiolitis and pneumonia, in those at extremes of age and also those with a compromised immune system, such as individuals who have had an organ or stem cell transplant or individuals with HIV infection.  Infection is more common in children than adults; serology studies suggest that most children have been infected by the age of 5.

“hMPV was first identified by Dutch resesarchers in 2001 in archived children’s respiratory samples in whom no bugs have been isolated, and has since been found worldwide.

“Seasonality is similar to that of influenza, with peak activity in winter/early spring, therefore high case numbers of hMPV identified in China may not be out of the ordinary.

“hMPV is probably less well studied, compared to other respiratory viruses, such as flu, SARS-CoV-2 than RSV.”

Dr Conall Watson, Consultant Epidemiologist at the UK Health Security Agency, said:

“hMPV is a common respiratory infection in winter, and we typically see activity reaching a peak at this time of year.  Infections are usually mild, causing symptoms of a common cold.  Our surveillance systems in GP surgeries and hospitals indicate that levels are in line with what we would expect to see.  Most people have had hMPV by the time they are five years old and catch it again throughout their lives.

“As with all respiratory viruses, you can help reduce infections being passed on through regular handwashing and catching coughs and sneezes in tissues and throwing them away.  If you have symptoms such as a high temperature, cough and feeling tired and achy, try to limit your contact with others, especially those who are vulnerable.  There are many viruses in circulation at the moment, including flu – if you have symptoms of a respiratory illness and you need to go out, our advice continues to be that you should consider wearing a face mask.”

Prof Martin Michaelis, Professor of Molecular Medicine, University of Kent, said:

What is the human metapneumovirus (HMPV)?

“The human metapneumovirus (HMPV) was discovered in 2001.  It belongs to the large group of viruses that cause common colds and flu-like diseases.  Like influenza viruses, coronaviruses (including SARS-CoV-2 that causes Covid-19), and its relative respiratory syncytial virus (RSV), HMPV has an RNA genome (i.e. it stores its genetic information in RNA molecules and not in DNA molecules like all living organisms, including microorganisms, plants, and animals).

What disease(s) are caused by HMPV?

“HMPV is very common.  At the age of five, almost everyone has been infected with HMPV.  It causes common cold-like diseases with symptoms including a cough, fever, and a runny and/ or congested nose.

“Young children, the elderly, and immunocompromised individuals can develop more severe disease such as bronchitis and pneumonia.

Are there treatments for HMPV, and how can I protect myself?

“No, there are no vaccines or drugs available for HMPV.  The only way of protecting yourself is by avoiding infections.  HMPV spreads via the air and contaminated surfaces.  Thus, protection measures are the same that we know from Covid-19 – they include thorough hand hygiene, avoiding contact with others, and wearing a face mask.  Being cautious will protect you and others, in particular vulnerable individuals, who are at an increased risk.

Why is HMPV in the news now?

“Most respiratory viruses, including HMPV, predominantly spread when it gets colder, when they are more stable and we spend more time indoors.

“Even before Covid-19, large outbreaks of respiratory illnesses put hospitals under pressure in the winter.  However, we did not care about the viruses that caused them.  Today, there is more interest in the causes of respiratory diseases, and this year there is a relative high number of HMPV cases.  However, you would be surprised how little we still know about common cold viruses in general.

Will HMPV cause another pandemic?

“This is extremely unlikely.  In contrast to SARS-CoV-2, the coronavirus that causes Covid-19, HMPV has been around for decades, and there are high levels of immunity in the population.”

Dr Andrew Catchpole, Chief Scientific Officer, hVIVO, said:

What is hMPV?

“hMPV is relatively common virus that causes cold symptoms. It is a member of the same virus family as RSV.  In healthy adults the infection would be expected to cause common cold like symptoms indistinguishable from many other common-cold causing viruses and not normally serious. Hence most infections in the population will go undiagnosed as people with colds do not normally have tests to identify the specific pathogen.  It can however, be serious in the elderly, immunocompromised or children.  Serious cases requiring hospitalisation are almost exclusively in these risk groups.”

Is this a new / unknown virus or do we already know a lot about hMPV?

“It was first discovered in 2001 but was likely around well before this and not identified.   It has been one of numerous common cold viruses that circulate every winter season each year, so no, it is not a new virus. 

Do we know this is what is happening in China; do we need more information?

“We know that there has been a surge in infections which have coincided with high rates of influenza and COVID putting health systems under considerable strain, just as they are in many other countries at present, including the UK, where we are seeing high levels of flu and COVID along with Norovirus.  hMPV is usually detected in the winter periods but it does seem that the rates of serious infection may be higher in China than what we would expect in a normal year.  We need more information on the specific strain that is circulating to start to understand if this is the usual circulating strains or if the virus causing high infection rates in China has some differences.

Whilst hMPV does mutate and change over time with new strains emerging, it is not a virus that we consider to have pandemic potential.  This is because the changes in hMPV are gradual and based on previously circulating strains. Pandemics occur when a totally new virus enters the human population, like for COVID-19.  Or in the case of influenza, when a totally new variant of the virus enters the human population by combination with a human version of the virus with that of an animal version of the virus from what is known as the animal reservoir.    There is no such animal reservoir of related viruses known for hMPV.  This means that even if the hMPV in China currently is a new variant of the virus, it is highly likely to be significantly related to previously circulating hMPV strains such that there will be some level of pre-existing immunity from exposure to related viruses previously, which will significantly reduce the disease burden in healthy people.  Young people have less developed immune systems and the elderly’s immune systems’ effectiveness has declined from when they were younger, hence they become more susceptible to more serious outcomes of infectious diseases.

Is this unusual in China or does this often happen in winter?

“hMPV is common part of the winter cold causing viruses in most countries with seasonality.  It is not usual to be a major concern for high numbers of hospitalisations but it is unclear just how high the numbers are or if issues are arising purely due to coinciding with high flu and COVID levels.

Any other comments about what we do and don’t know about the current situation based on what is being reported?

“hMPV is not a reportable disease and not normally specifically tested for unless a person is hospitalised with complications from cold-like symptoms so surveillance is not as robust and routine in most countries as it is for influenza.  Recent years have seen an increase in availability of diagnostic testing for the virus and recent success of the RSV vaccines has led to a significant increase in hMPV vaccine development as success in RSV has given expectation that success in vaccination for hMPV is also possible given it is a virus from the same family.  hVIVO’s challenge models played a pivotal role in the development of the RSV vaccines with our studies showing the first human data of clear vaccine efficacy against this important pathogen.  Consequently, hVIVO has now developed a hMPV challenge model so that this is available for the research community to help expediate hMPV vaccine development and treatment.”

Prof Peter Openshaw, Professor of Experimental Medicine and Dr Claudia Efstathiou Research Associate, Imperial College London, said:

What is hMPV? 

“Human Metapneumovirus. Related viruses cause a condition called ‘Swollen Head Disease of Chickens’ and rhinotracheitis of turkeys, but it’s not clear when metapneumovirus first adapted to human-to-human transmission. hMPV is a distant relative of RSV.  

Is this a new / unknown virus or do we already know a lot about hMPV? 

“First described in 2001, this awkwardly named common cold virus infects people of all ages. The illness it causes tends to be more severe in those who are very young (aged 1-5 years) or old (over 65). It has similarities to RSV but tends to affect children in the second year of life rather than the first and to peak later in the winter season (especially in older adults, who tend to peak a bit later than toddlers). It can be hard to detect, PCR not being completely reliable. There is no vaccine, but several trials are underway.

Do we know this is what is happening in China; do we need more information? 

“More information is always helpful, but there is no evidence so far that what’s being seen in China is much different from what’s being seen in Europe. It seems that it’s the summation of several common winter viral infections rather than a new or unknown virus. 

Is this unusual in China or does this often happen in winter? 

“There’s the usual co-occurrence of several winter viruses, together causing intense pressure on the healthcare system.

Any other comments about what we do and don’t know about the current situation based on what is being reported?

“Sensible precautions that prevent or reduce the spread of any of these winter viruses would be wise in those with symptoms.”

Prof Sir Andrew Pollard, Director of the Oxford Vaccine Group; Ashall Professor of Infection and Immunity; Pandemic Sciences Institute, University of Oxford, said:

“Human metapneumovirus virus is a common respiratory virus which was first identified almost a quarter of a century ago by Dutch scientists.  The virus is known to cause a respiratory Illness in babies and in the elderly which can result in hospitalisation but in most other age groups it simply causes the symptoms of a cold.  It is one of the many viruses which circulate in the winter and add to the winter pressures on the NHS.  The reports of respiratory infections in China in the past few days appear to be attributed to both influenza and this human meta pneumovirus, which is rather similar to the situation in the UK this week.  A vaccine for a similar virus, RSV, was launched by the NHS in 2024 and new vaccines are being developed which could protect against both RSV and human metapneumovirus in one jab.”

Prof John Tregoning, Professor in Vaccine Immunology, Imperial College London, said:

“HMPV (human metapneumovirus) is not a new virus, it was first isolated in 2001 but most likely has been circulating for much longer.  It has very similar symptoms (in children at least) to RSV (respiratory syncytial virus).  It is part of the cocktail of winter viruses that we are exposed to.

“As with all respiratory viruses, there will be a range of symptoms and severity.  Risk factors will include age (either very young or very old) and underlying immunosuppression.  Like other viruses it will transmit in coughs, sneezes and in droplets.  Protecting yourself by being in well ventilated, covering your mouth when you cough, washing your hands will all help.  It will present in the same way as flu, sars-cov-2, RSV, so the same advice applies for those affected – rest, take on fluids, try not to spread it to others.  If you do feel very unwell go to your GP.  As it is a virus, antibiotics won’t have any effect.”

Prof Paul Hunter, Professor in Medicine, UEA, said:

“Human Metapneumovirus was first really linked to respiratory infections about 25 years ago, but it has been around a lot longer, at least 65 years (https://pmc.ncbi.nlm.nih.gov/articles/PMC5795268/).  I supervised a PhD on the infection some years back where we looked particularly at coinfections with other respiratory pathogens.

“hPMV is a quite common respiratory infection that peaks in winter.  Almost every child will have at least one infection with hMPV by their fifth birthday and we can expect to go onto to have multiple reinfections throughout life.

“hPMV typically causes cold-like symptoms that recover by themselves within 2 to 5 days.  Just occasionally it can cause more severe disease in the elderly, the very young (under 2 years of age) or medically vulnerable.  It is one of the leading viral causes of respiratory infections in children under 5 years.  There is currently no vaccine and treatment if necessary is basically supportive.

“One of the issues involved in these types of infection is that they are being diagnosed more frequently as we move to molecular diagnostic panels, so it is not always easy to know whether year on year increases are due to actual increases or just because we are diagnosing a greater proportion of infections.

“In England we have seen a fairly marked increase in recent weeks (see here https://ukhsa-dashboard.data.gov.uk/respiratory-viruses/other-respiratory-viruses) – so far the peak % positivity is a little over what it was this time last year so no major difference to usual, unless infections positivity rates continue to increase in coming weeks.

“So overall, I don’t think there is currently any signs of a more serious global issue.”

Declared interests

Prof Antonia Ho: No CoI to declare.

Prof Martin Michaelis: “No conflicts of interest to declare.”

Dr Andrew Catchpole “Chief Scientific Officer at hVIVO and has no other interests to state.”

Prof Peter Openshaw “I have advised several vaccine companies on the science that underpins vaccine development for hMPV and other respiratory viruses.”

Prof Sir Andrew Pollard: “Professor Pollard is chair of JCVI which provides independent scientific advice on vaccines to DHSC.  The comment above is given as Director of the Oxford Vaccine Group, not as JCVI chair.”

Prof John Tregoning: “None for HMPV.  In general I do work with Sanofi on flu vaccines.”

Prof Paul Hunter: “No CoIs.”

For all other experts, no reply to our request for DOIs was received.

Scientists comment on the first human case of Avian flu detected in the UK, as announced by UKHSA. 

Prof Ed Hutchinson, Senior Lecturer, MRC-University of Glasgow Centre for Virus Research (MRC CVR), said:
How likely is it that the virus has or will spread human-to-human from this case?

“Because viruses are closely adapted to particular host species, it’s really hard for a bird flu virus to infect a human. This is why, despite the very high levels of H5N1 currently infecting wild and farmed birds, human infections with this virus are extremely rare, and normally only occur in people who have close contact with birds. Onward human-to-human transmission of a bird virus is even harder, and is exceptionally uncommon. Nothing has been reported suggesting that onward spread of bird flu to other humans has happened here. Nonetheless, health protection agencies will monitor carefully for any signs of human-to-human transmission around any case like this, so if the virus did evolve to become better at growing in humans this would be spotted as soon as possible.

What could be done to prevent future cases of H5N1?

“In the UK, the most important measures at the moment aim to reduce as much as possible the number of infections of farmed birds by H5N1, particularly from wild birds, and to understand where the most precautions need to be taken. The control measures announced over the weekend and ongoing surveillance by UKHSA and the APHA aim to do this. These were in place even before this human case was detected. Given the scale of the outbreak in wild birds, these measures will reduce the ongoing risk to farmed birds but they cannot eliminate it.

How worried should we be about this? How does the risk of contracting bird flu differ between people working in close contact with birds versus the general public?

“At the moment, this case is not a huge cause for concern. Although the virus is a serious infection for birds and the control measures are important for UK poultry, most of us do not have close contact with either wild or farmed birds, so the chances of most people becoming infected by a bird are very low. Every measure should be taken to minimise the risk of infection for people who work with or keep poultry, and the control measures announced over the weekend will help to reduce this risk. It’s good to hear that the person affected is currently well and that antiviral drugs have been offered to other people who may have been exposed. There is currently no sign of wider spread of this virus among humans and we have good surveillance for detecting viruses like this in the UK. If wider spread did occur the fact that we already have some reserves of vaccines and antiviral drugs would give us opportunities to intervene.

Any other information should readers know about the situation?

“Within the UK, it’s worth reminding people not to handle dead birds (particularly waterfowl) and to try and prevent pets from scavenging bird carcasses, and also to avoid feeding pets raw meat from birds. Sightings of dead or sick birds can be reported at https://www.gov.uk/guidance/report-dead-wild-birds or on 03459 33 55 77.  It’s also important to note that influenza viruses are killed quickly by heating, so there should be no risk to the public from properly-cooked eggs or poultry.

“This is the UK experience of a global outbreak of H5N1 in wild birds, and its effects are different in other parts of the world. In some regions the virus has become a major problem for mammals as well as birds. In South America H5N1 is causing devastating outbreaks in seals and sea-lions, while in the USA it has managed to adapt to dairy cattle and is being shed in their milk – something which has not yet happened in the UK. Different strains of the virus are also circulating in birds in different parts of the world, and it is possible that these strains might have different properties. In the USA and Canada there have been two recent cases of humans getting severely ill after catching H5N1 from birds, in one case sadly leading to the person’s death. This underscores the potential risks of H5N1 infections, but it is also worth nothing that the H5N1 viruses currently circulating in UK birds are from a different strain of the virus to the ones in North America. Because human infections are so rare, how likely each strains is to cause severe disease in humans is still unclear. As a backdrop to all of this, virologists are watching carefully for any sign that H5N1 influenza viruses might be adapting to grow better in humans. This would be an exceptionally unusual event, but to minimise the risk of future influenza pandemics it is crucial that situations like this are carefully monitored.”

Dr Natsuko Imai, Research Lead in Epidemics in Wellcome’s Infectious Disease team, said:

“While avian flu H5N1 is commonly transmitted between birds, humans can also become infected through contact with infected birds. However, so far, there have been no documented cases of human-to-human transmission. The case confirmed by UKHSA today is not the same strain as the one causing outbreaks in dairy cattle in the US, where there is concern that continued spread among mammals could lead to the virus evolving the ability to spread between humans. Effective response relies on collaboration and clear communication between human and animal health workers. Being prepared can save lives, and requires robust surveillance and prevention measures, such as good biosecurity on farms and contact tracing, especially in areas with close animal-human contact. Research into transmission patterns, and how viruses change to infect different species continues to inform these preparedness efforts and identify emerging threats before they become crises.”

Prof Sir Peter Horby, Professor of Emerging Infectious Diseases and Global Health, Centre of Tropical Medicine and Global Health, University of Oxford, said:

“Human cases of influenza A/H5N1 infection acquired from animals, usually poultry, are rare but not unexpected. Since 2003 more than 900 cases of human H5N1 infection have been reported to the World Health Organisation. Whilst close monitoring of the infected person and their close contacts is warranted, such infections are not a cause for alarm. We should only become worried if there is evidence of onward transmission from person-to-person, which might indicate the virus has adapted to humans. In all the human H5N1 infections detected to date there has been no evidence of meaningful person-to-person transmission.

“The primary way to reduce the risk of all animal influenza viruses to humans is to control the spread of these viruses in poultry and livestock and to invest in developing diagnostic tests, vaccines, and drugs.  It is sadly likely that at some point in future there will be an influenza pandemic, even if it’s not this virus.”

Prof Jonathan Ball, Deputy Vice-Chancellor, Liverpool School of Tropical Medicine; and Professor of Molecular Virology, Liverpool School of Tropical Medicine (LSTM), said:

“Avian H5N1 influenza, or ‘bird flu’, which as the name suggests circulates widely in wild birds, thankfully doesn’t transmit to humans very easily, and only really occurs in people who have regular contact with either wild birds or poultry. Even in the rare cases where people do become infected, onward human to human transmission is very unlikely.

“However, that doesn’t mean we can be complacent. There is always the risk that the virus can evolve and become better adapted to spread amongst humans, so it’s important to be vigilant, to ensure good wild fowl and poultry surveillance and when human cases do occur, to isolate the patient to remove the risk of onward transmission.

Dr Alastair Ward, Associate Professor of Biodiversity and Ecosystem; Programme Lead for Zoology, University of Leeds, said:

What could be done to prevent future cases of H5N1?

“Adherence to biosecurity best practice, including the use of PPE and disinfection when handing poultry or material that may have been contaminated by them, may limit transmission of H5N1 from infected poultry to humans. Reporting of symptoms observed within a poultry flock to the Animal and Plant Health Agency, and subsequent statutory testing and control measures are critical for preventing further spread among birds, as they have been in this case.

How worried should we be about this? How does the risk of contracting bird flu differ between people working in close contact with birds versus the general public?

“The UKHSA and APHA have avian influenzas under ongoing surveillance. We know what the genetic changes are that make the viruses more likely to jump to humans and to transmit between humans, and they have not been detected in the UK. Risks to the general public likely remain very low. Risks to people who work in close contact with birds, particularly ducks, geese, swans, chickens and turkeys are greater, but can be reduced by implementing biosecurity best-practice, including use of PPE and disinfection when making contact with birds or material that has been contaminated by them.

Professor Wendy Barclay FMedSci, Regius Professor of Infectious Disease at Imperial College London, said:

“Since the number of cases of H5N1 in poultry premises has increased again this winter, this is not unexpected. 

“It’s important to remember that bird flu does not transmit readily between people without several simultaneous adaptive mutations in different genes. 

“Genetic sequencing would confirm if this has happened, but with just one individual case, it is highly unlikely.”

Declared interests

Prof Ed Hutchinson “I have received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). I have unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical. My group receives funding from the Wellcome Trust and from UKRI, including from the FluTrailMAP(One Health) consortium which aims to respond to H5N1 in mammals.”

Dr Natsuko Imai None

Prof Sir Peter Horby “I receive philanthropic funding from FluLab for a clinical trial of treatments for patients hospitalised with infleunza.”

Prof Johnathan Ball: None

Dr Alastair Ward I am a member of the FluMAP and Flu:TrailMAP consortia: multi-disciplinary groups of scientists funded by UKRI and Defra to better understand the ongoing H5N1 panzootic and how to better control it.

Prof Andrew Preston I have received research funding from several companies that make vaccines, but not for any work related to influenza.

For all other experts, no reply to our request for DOIs was received. 

Scientists comment to an unknown disease breakout in the Democratic Republic of Congo (DRC). 

Dr Amanda Rojek, Senior Clinical Fellow, Pandemic Sciences Institute, University of Oxford, said:

“The exact cause of these outbreaks is unknown. While there might be one disease that explains all cases, we frequently see situations where there might be a mixture of more common illnesses contributing to case numbers. It is reassuring that tests for Ebola and Marburg virus – two viral haemorrhagic fevers with a high death rate – have returned negative so far.

“Investigations will now be underway to examine the cause of the outbreak – which could include infectious diseases, or diseases caused by exposures to toxic or contaminated substances. Local health care teams will also be trying to identify how cases might be linked to each other.

“The outbreak investigation team will be verifying reports of a bat being consumed by children who later died of their illness because this raises the possibility of a zoonotic disease – that is, a disease spread from animals to humans. However, rumours are often rife early during an outbreak, and so verification of this information is important.

“Scientific research has a crucial role to play in understanding an outbreak of this kind, to ensure that responses are evidence-based, and that national health agencies can make the best possible decisions.

“Support for local health care services will also be very important, because these outbreaks are occurring in a vulnerable area with poor healthcare infrastructure.

Dr Zania Stamataki, Associate Professor in Viral Immunology, University of Birmingham, said:

What do we know about the outbreak, potential causes, or modes of transmission?

“The symptoms shown in these infections are different to the alarming infection caused by severe malaria in the DRC in the end of last year, with patients reporting nose bleeds, vomiting blood and internal bleeding. The time from symptom onset to death is 48 hours, which is very alarming.

“We know that the patients tested negative for known haemorrhagic fever viruses such as Marburg and Ebola. Other haemorrhagic fever-causing pathogens are investigated.

“The modes of transmission are unknown. The authorities are also looking at culprits beyond infection, for example poisoning by a toxic agent.

How is the situation being controlled, Are we likely to see more cases in the coming days?

“It is possible that we will see more cases. The incidents are currently correctly treated like an outbreak of infection, but it is not known how infection is transmitted, which makes it more difficult to contain. The best way to contain the outbreak is to isolate patients and stop travel in affected regions to prevent transmission.

“Viral infections can remain silent in the body for days before we start showing any symptoms. This is called the virus “incubation period”.  While infected, a person could feel well enough to travel and mix with others in social events, which aids transmission.

How likely is it that this disease will spread across borders, potentially into the UK?

“Infections know no borders and do not respect country lines. People travel and infections travel with them, either hitching a ride in a person or in animal carriers, so one cannot exclude spread outside of a country’s borders. In the UK and in other countries we need to remain vigilant and watch for symptoms. Symptoms of a haemorrhagic fever-type disease should be reported to the UK Health Security Agency via a registered medical practitioner.  

Given the large number of deaths and rapid transmission how concerned should we be?

“This outbreak, as well as previous outbreaks in the DRC are of significance to the rest of the world and we need to keep a close eye and assist with diagnosis and treatment. The large number of deaths of children and young people may be worsened by malnutrition and pre-existing conditions like malaria, that could weaken the immune system.

Could the pathogen have come from a bat, and what might this tell us of the nature of the outbreak?

“There are reports of three children eating a dead bat, so people rightly ask if this outbreak could be due to a bat-related virus infection. It is unwise to seek contact with dead bats, given that they are natural reservoirs of deadly viruses. Bats carry many viruses that have previously jumped to infect humans and cause severe diseases, including viruses such as Ebola, Marburg, Nipah, Hendra severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory coronavirus (MERS-CoV) and SARS-CoV-2, which caused the COVID-19 pandemic. If the infection originated from a virus that came from a bat, this tells us that it is unlikely that we have pre-existing immunity to this new infection for humans, so we are unprotected, we suffer severe disease and even death. If the virus is similar to other viruses infecting humans, like the covid-causing virus was similar to some common cold coronaviruses, some people may stand a chance to show less severe symptoms and recover.”

Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:

“At time of writing, there is a huge amount of uncertainty about this outbreak.

“Outbreaks like this will happen many times around the world.  Typically, such outbreaks are brought under control relatively quickly. However, here, it is concerning that we have hundreds of cases and over 50 deaths, with haemorrhagic-fever like symptoms widely reported among those cases.

“Tests have so far proven negative for Ebola and other similar viruses, but results are known for a relatively small number of cases. Tests are never 100% accurate, and it is likely that with increased testing, we will have a confirmed pathogen in some of those samples.

“The lack of healthcare infrastructure in the DRC means the public health response is more complicated.  However, the country has had mpox and Ebola outbreaks in recent, so they are experienced at addressing infectious disease epidemics.”

Prof Paul Hunter, Professor in Medicine, University of East Anglia (UEA), said:

“This is another cluster of fatalities in one of the poorer African countries. These are not rare. We saw another such cluster in DRC last November/December time. That last one turned out to be malaria and the was likely more severe as a result of increased malnutrition.

“So far I am not aware of much information about the current problem other than it is in the northwest of the country there are apparently two separate clusters in the area.  The earlier cluster was reported in 21 January 2025 and is centred on Boloko Village in Bolomba Health District. The more recent cluster is in Bomate Village in Basankusu Health Zone and this was reported on the 9^th February. No link is known between these two clusters. So far test results are negative foe Ebola and Marburg.

“The only other bit of information is that in the earlier cluster some of the children who died had apparently consumed bat carcasses. But the relevance of that is not yet known.

“What is causing these two clusters is not yet known or indeed whether the same thing is responsible for both. It is certainly possible that we have a similar issue to last autumn with malaria and malnutrition. But we need to wait the results of ongoing investigations to know the cause.”

Declared interests

Dr Amanda Rojek “None”

Dr Michael Head “None”

Prof Paul Hunter “None”

For all other experts, no reply was received for our request for DOIs. 

Scientists comment on the potential of a second norovirus wave. 

Dr Damien Tully, Associate Professor at the Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine (MRC/UVRI and LSHTM) Uganda Research Unit, said:

“Since 2012, there has been one dominant norovirus variant circulating in the UK called GII.4. The surge in norovirus activity this season is due to a new variant of a different type of norovirus called GII.17 which, over the last seven years, has circulated at low levels and has only been responsible for around 1% of cases.

“Given the current variant’s low prevalence over past years, most people are susceptible to infection, which explains the huge surge in cases. Similarly, we know that infection with the variant that has previously caused the majority of cases (GII.4) will not confer any immunity to other strains of norovirus, so those who have experienced infection will still be susceptible to other strains.

“Reduced population immunity due to lower exposure during COVID-19 may have also created an environment where multiple strains can spread more easily.

“The second wave, while a cause for concern, should not be entirely surprising, as the GII.4 strain has dominated for over a decade and is a tough competitor. Time will tell if the new GII.17 variant can end GII.4’s 12-year reign as the dominant strain.

“The secret behind GII.17’s sudden success is still under investigation but through our research, we are continuing to find clues from the virus’s genome that may explain why it’s behaving differently. The new strain is evolving between 3 and 6 times faster compared to other GII.17 variants and changes to its structure may be affecting its ability to infect us.

“Uncovering the clues to norovirus’s success will help us unlock the potential for a vaccine, hopefully in the near future.

“The best advice is to be diligent with hand washing with soap and warm water, as alcohol-based hand sanitisers or gels do not kill the virus. Norovirus can also survive on surfaces for days but bleach or other disinfectants are effective against it.

“While to most of us infection with norovirus may just be annoying, it can have significant consequences for vulnerable groups, like the elderly, and for those whose job requires them to be in contact with many people a day, like healthcare workers. So any step you can take in preventing norovirus spread is important.”

Prof Paul Hunter, Professor in Medicine, University of East Anglia

How concerning is this potential second wave of norovirus?

“A double peak for norovirus is not unusual. We saw the same thing last winter and in 2020/21 winter but not so much in 2022/23.

How unusual is it to see two different strains within a season?

“Not at all unusual and indeed is the norm, though one tends to predominate.

“A year ago 83% were genogroup 2 (GII) and 17% (127 out of 770) were genogroup 1 (GI). The most frequent norovirus GII genotypes identified were GII.4 (42%) and GII.3 (19%), the most frequently identified norovirus GI genotypes were GI.3 (8%) and GI.6 (4%).

“Two years ago 90% were genogroup 2 (GII), 8% were genogroup one (GI) and 2% were mixed. The 3 most frequent norovirus GII genotypes identified were GII.4 (48%), GII.3 (13%) and GII.2 (10%) and the most frequently identified norovirus GI genotypes were GI.3 (3%) and GI.6 (3%).

“So we usually see quite a variety of genotypes each year.

How does this pattern compare to previous/ typical years?

“It is following roughly the same pattern as previous years more or less but somewhat greater number of cases.

“So far this season (2024/25) up to week 7 the cumulative number of positive norovirus laboratory reports stands at 9,289 in England.

“The equivalent number last year up to week 7 was only 4,855 and the year before that 4,551. So this represents quite a jump.

Do we know what causes something like this to happen?

“I don’t think we really know why such infections are as high this year

“Partly it will be down to better diagnostics. Testing for norovirus has become increasingly common in recent years as a result of new technology and so some of this increase will be an artifact of increased testing.

“Low population immunity as a result of low infection levels as a result of the covid controls will also be playing a role.

“There may well be some impact due to different variants becoming prominent in much the same way as we saw with covid variants, although there is no really new variant of norovirus as far as I can tell.”

Professor Arlene Wellman MBE, Group Chief Nurse for St George’s, Epsom and St Helier, said:

“Once norovirus enters a hospital, it can rip through our wards like wildfire, making patients even sicker. We are doing everything we can to limit the spread, but you can help us.

“Hand sanitisers such as alcohol gel do not kill the bug – the simple act of good hand washing with soap and water can make all the difference between our beds being used to care for patients, or lying empty at a time when every bed is precious.”

https://ukhsa-newsroom.prgloo.com/news/ukhsa-warns-of-potential-second-norovirus-wave

Declared interests

No reply to our request for DOIs was received.

Scientists comment on the first case of Avian Flu (H5N1) confirmed in a sheep in Yorkshire. 

Dr Colin Butter, Associate Professor in Bioveterinary Science, University of Lincoln, said:

“The premises on which the single infected sheep was found had previously been home to birds that became infected with avian influenza, giving the possibility of faecal oral transmission of virus.    This cross-species infection is unsurprising, given that birds and sheep share the same molecular receptor that allows virus to gain access, and then replicate in, the host animals’ cells.  Whilst the prevalence of influenza in poultry and wild birds remains high, further limited incursions into farm species should be expected

“There is little immediate threat to humans from isolated infections of sheep, as normal cooking of meat and pasteurization of milk readily kills the virus. 

“However, it will be important to understand if sheep can transmit the virus to other sheep as any further spread would allow genetic mutation and inter-species contact that might eventually lead to transmission into other species, including humans.”

Professor Ashley Banyard, Head of the National Reference Laboratory for Avian Influenza at the Animal Plant Health Agency, said

“The first global detection of HN51 in samples from a sheep is significant, but not totally unexpected given we have seen infected dairy cows and pigs in other countries. This detection is the result of an unusual exposure event to infectious viral material in a backyard setting where infected poultry had been previously housed.

“This detection was limited to a single animal and the infection pathway was most likely via co-located infected poultry. This underpins the importance of the UK’s approach in sampling and testing where there is evidence for increased risk of exposure to non-avian species following detection in poultry and underlines the importance of scrupulous biosecurity. The broader risk to sheep is considered very low”

Dr David Allen, Associate Professor in Virology, University of Surrey, said:

“The report from APHA & Defra of a case of H5N1 type influenza of avian origin in a sheep is noteworthy, as this is the first time the virus has been reported in a sheep. The case reported today was found through the routine surveillance programme, highlighting the importance of these surveillance systems.

“The H5 subtype of the influenza virus usually infects birds but can also infect mammals. There have been reports of avian-origin influenza virus infecting mammalian livestock in other countries: for example, avian-origin influenza has been detected in dairy cows in the USA, and last year the virus was detected in goats.

“In the case reported today, the sheep was on a premises where the avian influenza virus was present in captive bird flocks, which suggests transmission of the virus from these birds to the sheep. But as a single case in the sheep that has been managed, risks remain low.

“The quick identification of, and response to, the detection in a sheep has confirmed this is a single case, as further testing has shown no further infections on the affected premises. As such, risks to livestock remains low. However, it highlights the importance of maintaining strict biosecurity measures on premises.

“Avian-origin influenza viruses, like the H5N1 subtype, are primarily diseases of birds but have on rare occasions been reported in humans. Current evidence suggests the circulating avian-origin influenza viruses do not spread easily to humans, so the risk to the general public remains very low. However, but people should be aware of advice to not touch any dead or sick wild birds they find.”

Prof James Wood, Infectious Disease Epidemiologist at the University of Cambridge and Co-Director of Cambridge Infectious Diseases, University of Cambridge, said:

“This is a very important finding. It is the first case of a domesticated animal getting infected with avian influenza H5N1 over the 5 years or so of the current epidemic in wild birds and poultry. The case was detected in a sheep which reportedly had multiple positive tests in its milk and was on a farm clearly undergoing heightened surveillance as cases of the notifiable disease had been detected there in domestic poultry. Few details are yet available, but it seems reasonable to infer that the sheep was infected by close contact with infected birds or fomites from them on the same farm.

“Detection in milk is reported and some outlets report that lambs were tested and none found positive. It is not clear if this was a sheep being milked for human consumption or one that was only nursing lambs. No other sheep in contact were found to be positive.

“The case appears to have worrying parallels with the dairy cattle situation in the US, but also some reassuring differences. The case is one in which a mammary infection was found, as in the US cattle, but thankfully no within farm spread has been found. In the US, transmission between cattle is thought to have been mostly from the milking process. Differences in how sheep are milked (when they are) may make transmission risks lower than in dairy cattle – or the level of mammary infection may be different in sheep; it is hard to infer much from single cases. The surveillance in animals on the farm is a stark contrast to what has been done in the US; the simple act of stopping movement from infected farms can be expected to halt any farm to farm spread of this disease in sheep.

“While this is an important observation, it doesn’t change the global or national situation. Risks from avian influenza remain high and all care needs to be taken to ensure that there is no transmission from infected farms. Mammals in contact with avian influenza outbreaks will from time to time become infected and may become ill or die. Defra has announced this morning that they have updated their case definition for avian influenza in kept (and wild) mammals which will enhance their ability to control outbreaks. The heightened awareness of this potential transmission may result in other cases being found, should the current numbers of avian influenza outbreaks on poultry farms continue, despite the knowledge that strong biosecurity can prevent most of them. Pasteurisation of milk inactivates the risks to human health from avian influenza virus in it.”

Prof Ed Hutchinson, Professor of Molecular and Cellular Virology, MRC-University of Glasgow Centre for Virus Research (MRC CVR), said:

“Influenza viruses are common in wild birds. Over the last five years, a particularly aggressive strain of the H5N1 avian influenza virus has spread through bird populations across the world. On the way, it has caused repeated ‘spillover’ infections of mammals: mammals that wouldn’t normally get avian influenza have caught the disease from birds. Usually these are one-off infections that don’t go any further, although last year the virus began to spread widely among dairy cattle in the USA, demonstrating the potential influenza viruses have for adapting to new species.

“The emergence of avian influenza in cattle last year was surprising, as normally cattle don’t catch this type of influenza (influenza A virus). Another animal we hadn’t previously thought of as a host for influenza A viruses is sheep, which makes this announcement of H5N1 influenza in a single sheep in Yorkshire startling. Sheep haven’t previously been thought of as hosts for influenza A viruses, although last year in the USA young goats did get infected with H5N1 at a farm in Minnesota – in this case, this was a one-off infection that didn’t go any further.

“The sheep was on a farm where avian influenza was present in captive birds, suggesting an obvious route of transmission from wild birds to captive birds to the sheep.

“The fact that the virus was detected in the sheep’s milk is also surprising. It suggests parallels to the ongoing H5N1 outbreak in dairy cattle in the USA, where the virus is spreading through cow’s milk. At the moment there is no evidence of any ongoing transmission from the sheep, and the case appears to have been contained.

“More work will be needed to understand what’s going on here – in particular to understand if this is a very rare or one-off event which happened because there was a lot of H5N1 around and this was just the wrong sheep in the wrong place, or whether sheep infections with H5N1 might become more common in the future. Ongoing surveillance will be needed to understand the risk this virus poses to the welfare of sheep as well as to food security.

“In terms of direct risk to humans, we know from the dairy outbreak in the USA that H5N1 in milk is a possible source of human infection. H5N1 can cause severe illness in humans and it is important to minimise the risk of farmed animals infecting them, although so far in the USA human cases of H5N1 contracted from cows in dairies have typically been quite mild. There is also a risk of H5N1 ‘breeding’ with human strains of influenza to produce a new human influenza virus. There is no evidence that this has happened anywhere with an H5N1 virus, but it is important that we work hard to keep that risk as low as possible.

“A single infected sheep does not pose a significant risk to humans, particularly because it looks as if the farmer, DEFRA and the APHA have worked together effectively to contain and monitor the situation. However, H5N1 is globally distributed in birds, and if it did become clear that this was not a one-off and that sheep are at risk of infection then this would have implications for surveillance and farm biosecurity in any country with sheep farming. For the time being, this is one to keep an eye on, but not to get too alarmed about.”

Professor Ian Brown, Group Leader at the Pirbright Institute, said:

“The detection of H5 highly pathogenic avian influenza (HPAI) in the mammary gland of sheep which has had close contact with infected birds is not an unexpected finding. Proactivity in looking for spillover to domestic mammals has been strengthened in the UK subsequent to the spread of infection amongst USA dairy cattle. The threat to animals and humans remains unchanged since such spillover we have learnt is possible when close contact occurs between multiple infected species. It is too early to consider whether such virus is capable of onward spread within sheep but this was an isolated small holding with a small number of birds and sheep. The pathways of spread of these viruses in the USA has been shown to be by movement of dairy cattle in commercial milking herds which appears not applicable in this single case of one animal becoming infected. It does emphasise the importance of separating species and maintaining good farm hygiene.”

https://www.gov.uk/government/news/influenza-of-avian-origin-confirmed-in-a-sheep-in-yorkshire  

Declared interests

Dr Colin Butter: I have no conflicts of interest regarding this statement.

Dr David Allen: I have previously worked for the predecessor organisations of UKHSA (i.e. Health Protection Agency and Public Health England) between 2009-2017.

Prof James Wood: James Wood is supported by BBSRC and Defra as part of a national consortium (Flu Trail Map) to address the challenges coming from avian influenza.

Prof Ed Hutchinson: I have received honoraria for work in a steering group of the Centre for Open Science (Open Practices in Influenza Research; 2021-2022) and on an advisory board for Seqirus (2022). I have unpaid positions on the board of the European Scientific Working group on Influenza and other respiratory viruses (ESWI) and as a scientific adviser to PinPoint Medical. I am part of FluTrailMAP(OneHealth), a UKRI-funded research consortium aiming to respond to H5N1.

Prof Ian Brown: IB receives research funding to study avian influenza in multiple hosts. IB is a member of the UK scientific committee ‘New and Emerging Respiratory Threats Assessment Group’. IB participates in UKHSA led fora that assess the risk to human health from avian influenza viruses.

For all other experts, no reply to our request for DOIs was received.

Scientists comment on the UK Health Security Agency’s new Priority Pathogens reference tool for R&D funders.

Dr Catrin Moore, Reader in Global Health and Infectious Diseases at St George’s, University of London, and co-Chair of the Microbiology Society’s Impact and Influence Committee, said:

“The tool is useful in bringing a lot of information together in one place.  The work as described fits my understanding of pandemic/epidemic potential, and vaccine availability.  I would however like to understand how they came to these conclusions, what methods they used and which papers they took the information from.  I’m also keen to see the diagnostics to understand which diagnostics the team could find.

“It is difficult to determine the quality of the research presented in the report given there are no references, no information on where the data was derived from and the authors are not listed on the report.

“There will be more susceptible people within the general populations who will be at more risk of disease compared to others which are not described in this work.  Also there are some notable omissions, for example Mycobacterium tuberculosis which was recently added to the World Health Organizations Bacterial Priority Pathogens List, 2024.

“Without understanding the methodology used in this work it is difficult to understand whether there is any overspeculation.  The team have brought together a good list to begin with, however I would like to see more evidence to back up their tool and the methodology behind the results they have published.”

Prof Jose Vazquez-Boland, Chair of Infectious Diseases, University of Edinburgh, said:

“The establishment of these priority lists is a double-edged sword when it comes to research into pathogens and infectious diseases.

“While at first glance it may seem like a logical step and could indeed help streamline and focus research efforts, the intended prioritization comes with a risk.

“In a context where research funding and resources are increasingly scarce, research on pathogens or infections that, while still very important, are not on the priority list could receive insufficient or no funding.

“This would have negative consequences, as only a comprehensive understanding of a diversity of pathogens and the common themes and specificities in their infection biology can facilitate the identification of intervention targets or rational control measures, or more accurate predictions in terms of emergence of new threats in response to ecosystem changes – which may involve “non-priority” pathogens.

“In my opinion, the bacterial pathogens list is rather limited and predictable.  It also omits as a research priority on its own critical cross-cutting issues, such as antimicrobial resistance, which by its very nature can be horizontally transferred between different bacterial pathogen groups/families.”

Prof Emma Thomson, Director of the MRC-University of Glasgow Centre for Virus Research, said:

“The UKHSA’s new Priority Pathogens reference tool is an important and valuable resource that will help to guide national research efforts and improve preparedness for future infectious disease threats in the UK.  By highlighting pathogen families of greatest concern to public health, this tool will enable more strategic investment in diagnostics, vaccines, and therapeutics, focusing attention where it can have the greatest impact.  From a scientific perspective, the list is particularly helpful in identifying gaps in our current understanding of high-risk pathogen families and the areas where new research and countermeasure development are most urgently needed.  Many of the listed families—such as Coronaviridae, Paramyxoviridae, and Orthomyxoviridae—are already recognised as significant threats, but the tool also highlights less well-characterised families where pandemic or epidemic potential remains underexplored.

“It is essential that this list remains dynamic and responsive to emerging threats.  History has shown that pandemic risks can arise from unexpected sources.  For example, coronaviruses and retroviruses were not widely regarded as major threats before SARS-CoV-1 and HIV-1 emerged, respectively.  Flexibility and regular reassessment of the list will be crucial to ensure preparedness keeps pace with the evolving pathogen landscape.  The concept of Disease X also remains critical in this context.  There are an estimated 320,000 undiscovered viruses in wildlife that could have spillover potential.  Enhanced technologies for virus discovery and characterisation—such as unbiased metagenomic sequencing and improved surveillance—will be essential to ensure that novel pathogens are rapidly identified and assessed for pandemic potential.  The UKHSA tool provides a strong and vital framework for guiding preparedness, but it must retain flexibility to account for emerging pathogens that have not yet been recognised, an issue that is recognised by UKHSA via its mSCAPE programme.

“The MRC-University of Glasgow Centre for Virus Research strongly supports UKHSA’s effort to provide a structured framework for research prioritisation.  This tool will not only help scientists focus their efforts but will also strengthen collaborations between academia, industry, and public health agencies.  The integration of this reference tool into the broader UK Biological Security Strategy represents a strategic step forward in building resilience against future infectious disease threats.”

Prof Martin Hibberd, Professor of Emerging Infectious Disease, London School of Hygiene & Tropical Medicine (LSHTM), said:

“I am pleased to see a guidance description for pathogens in a UK context being released, and that it will be up-dated yearly. As mentioned in the report, these lists cannot be comprehensive and different perspectives are likely to lead to different conclusions, but it’s release is likely to lead to more widespread consultations and honing of the findings for next year. While all the pathogen families are important, the three identified as priorities (Covid-19; Nipah virus; and avian influenza) are not surprising and I expect perhaps a more detailed, UK specific, priority list next year.”

Darius Hughes, UK General Manager at Moderna, said:

“This important work directly supports Moderna’s strategic partnership with the UK Government to strengthen national pandemic preparedness. By aligning our scientific innovation with the UKHSA’s priority pathogen list, we can help accelerate the development of vaccines where they are most urgently needed. This ensures our joint efforts are focused, forward-looking, and capable of responding rapidly to emerging biological threats—ultimately supporting the UK’s ambition to lead in global health security and protect public health through sustained innovation and collaboration.”

Prof Miles Carroll, Professor of Emerging Viruses, Pandemic Sciences Institute, University of Oxford, said:

“This new Priority Pathogen Families R&D Tool from UK Health Security Agency is aligned with similar prioritisation from the UK Vaccines Network and the World Health Organization, but with a UK focus for obvious reasons.

“The new R&D Tool is consistent with existing evidence, which is helping guide funders, policymakers and scientists on the most urgent research gaps in epidemic and pandemic pathogen threats.  Tools like this are important if we are to develop effective diagnostics, vaccines and treatments to support the UK Biological Security strategy.”

Prof Robert Read, Professor of Infectious Diseases, University of Southampton, and Editor in Chief, Journal of Infection, said:

“Lists like this have been made for many years, and they represent an effort to prioritise infections for advisory and funding purposes, ostensibly to align research funding as closely as possible to public health need.  Unfortunately, pathogens emerge or change constantly, and it is difficult to predict big infectious disease problems coming down the line.  For this reason, I think this list is at best pointless, and at worst potentially harmful to the public health.

“Pointless because the list of viruses is so long that its tricky to name a significant viral pathogen that has not been included.  Potentially harmful because a prescriptive list like this could misdirect funding towards certain infections, and away from problems that need urgently to be solved.  For example, the list of bacteria of concern includes Yersinia pestis (the cause of plague, a massive problem in 14th-18th Century Europe) for which there is now good available treatment and potential vaccine candidates, but does not include Bordetella pertussis (the cause of Whooping Cough) which caused serious problems for the public during 2024 because vaccines remain sub-optimal and antibiotic treatment only works during the early phase.”

Prof Mark Woolhouse, Professor of Infectious Disease Epidemiology, and Director of the Tackling Infections to Benefit Africa, University of Edinburgh, said:

“A key recommendation of the UK Covid Inquiry’s Interim Report for Module 1 (Preparedness) was that prior to 2020 the UK was overly focussed on the risk of an influenza pandemic.  When Covid arrived, it took too long to adjust our response to a different threat, which was part of the reason we ended up in lockdown.

“Since the pandemic, there have been many initiatives to better understand the diversity of pandemic threats that the UK and the world may face in the coming years.  The UKHSA’s pathogen prioritization exercise is a welcome contribution to this global effort.

“Of the highest priority pathogens identified by the UKHSA, no one could argue with the inclusion of coronaviruses and influenza viruses (the latter being members of the Orthomyxoviridae family).

“The UKHSA are also right to be concerned about another family of viruses, the Paramyxoviridae.  This is a group that includes the measles virus, itself a continuing cause for concern with large outbreaks regularly reported from around the world.

“A novel measles-like virus would pose a threat far worse than Covid.  Such a virus would have a much higher R number than the original variants of Covid – making it impossible to control by even the strictest lockdown.  It would also be considerably more deadly, and (unlike Covid) it would be a threat to children.  This is the kind of pandemic that public health agencies around the world are most concerned about.

“That said, there are many potential kinds of novel pandemic threats – so-called Disease X – and the UKHSA report is a timely reminder that we should not put all our eggs in one basket.  The possibility of different kinds of threat – different transmission routes, different types of disease, different populations at risk – means that our response needs to be scalable, adaptable and quick.  Knowledge, information and data collected in the first few weeks of the next pandemic will be crucial to tailoring our response appropriately.  We need the systems to gather that data in place in advance and ready to be activated, possibly at very short notice.”

‘Priority pathogen families research and development (R&D) tool: A reference tool to help guide England-based funders of research and development’ was published by the UK Health Security Agency at 00:01 UK time on Tuesday 25 March 2025.

Declared interests

Dr Catrin Moore: “No conflicts of interest to declare.”

Prof Jose Vazquez-Boland: “I declare I have no conflict of interest.”

Prof Mark Woolhouse: “I am a consultant for the Coalition for Epidemic Preparedness Innovation (CEPI) and a member of the Scottish Committee for Pandemic Preparedness (SCoPP).”

Prof Martin Hibberd: “I have no conflicts with this topic, but I do work on some of the pathogens listed and have been funded by Industry (most recently J&J) – amongst other government support, to work on them.”

Prof Miles Carroll: “I consult for PicturaBio diagnostics. I am a member of the WHO R&D BluePrint Pathogen Prioritisation Committee, UKVN, APHA SAB and MRC/UVRI SAB.”

Darius Hughes: In December 2023, Moderna entered a 10-year strategic partnership with the UK government to establish an mRNA research development and manufacturing facility in the UK. The strategic partnership is managed by the UK Health Security Agency on behalf of the UK government.

For all other experts, no reply to our request for DOIs was received.

Scientists comment on a case of Clade 1b Mpox in an individual with no links to other cases, as confirmed by the UK Health Security Agency (UKHSA). 

Dr Jonas Albarnaz, Institute Fellow, Capripoxvirus Biology, The Pirbright Institute, said:

“Mpox presents as a skin rash with lesions (blisters) in any part of the body, including the palms of the hands, soles of the feet, mouth, genitals, and anus. Mpox rash can be confused with chickenpox. The mode of transmission of mpox is via close contact, and sustained human-to-human transmission has driven the current outbreak of clade 1b mpox in DRC and other countries in Central Africa, as well as the cases imported into countries outside Africa. So far, the clade 1b cases in the UK have been in individuals with recent travel history to Africa and their household contacts. The detection of a clade 1b case in a person without travel history or contact with the other clade 1b cases is surprising. Public health authorities should investigate how this recent case was acquired, but it’s likely that it was acquired from another infected person, via direct contact either with skin lesions or with contaminated surfaces or objects.

“Transmission of mpox from an asymptomatic person has been reported, but there’s limited information about the role of asymptomatic transmission in driving mpox outbreaks. Zoonotic transmission (animal to human) of mpox also occurs in endemic countries in Africa, but this is an extremely unlikely scenario given the absence of an animal reservoir in the UK.

“Vaccination remains the best strategy to prevent mpox and is recommended to individuals at higher risk of infection, which include contacts of mpox cases, healthcare workers, and people with multiple sexual partners. Two vaccines are approved against mpox: MVA-BN and LC16. These vaccines are based on weakened versions of a related orthopoxvirus (vaccinia) and were developed against smallpox. However, availability of these vaccines is very limited globally, representing a major bottleneck for the control strategies. It’s up to health authorities to decide on the most efficient strategy to deploy the available vaccine stocks. Ring vaccination, vaccination of close contacts of an infected person, is a common strategy to stop the chain of transmission of the pathogen infection.”

https://www.gov.uk/government/news/ukhsa-detects-first-case-of-clade-ib-mpox

Declared interests

Dr Jonas Albarnaz “No conflicts of interest to declare”

Scientists comment on the World Health Assembly adopting the World Health Organisation’s (WHO) Pandemic Agreement.

Prof Emma Thomson, Director of the MRC-University of Glasgow Centre for Virus Research, said:

“The adoption of this agreement is a major step forward for global pandemic preparedness.  It reflects a growing international consensus that equitable access to surveillance, diagnostics, vaccines, and therapeutics is not just a moral imperative, but a scientific necessity.  The commitment to strengthen global data sharing, including genomic surveillance, is particularly encouraging.  While details on implementation will be crucial, this framework provides a strong foundation for more coordinated, science-led responses to future health threats.  For the UK, it’s an opportunity to reinforce both our domestic preparedness and our support for international collaboration.”

Prof Alice Hughes, Group Leader Biodiversity Analytics of Terrestrial Ecosystems (BAT) group, University of Hong Kong, said:

“This is a very important document, and a major step forwards.  However, I feel it could have been stronger in calling out some of the higher risk interactions and the need for monitoring and management to mitigate risk.  This includes the destruction of native habitats, especially in areas which may dramatically increase the risk of spillover, the role of wildlife trade and fur farms, and the need for biomonitoring, and the appreciation of the need for the recognition of ecology as a key element in understanding potential risks which vary across space, time, and life-history phases.”

Jeremy Knox, Head of Infectious Disease Policy, Wellcome, said:

“In order to ensure an equitable effective response to future health emergencies, we need a worldwide consensus on how best to prepare.  The Pandemic Agreement is a significant and important step in establishing this.  Despite a challenging geopolitical environment, it is to be commended that member states have united after a long and difficult negotiation process to commit to improving how the world responds to global health crises.

“We now need a sustained and persistent effort to achieve the agreement’s ambitions on issues such as making R&D, access to vaccines, therapeutics, and diagnostics more equitable in an emergency.  Achieving this will require Governments, as well as public and private sector partnerships, to work together to build on this momentum of cooperation to deliver a more resilient, equitable approach to tackling future epidemics or pandemics.”

Prof Stephen Griffin, Professor of Cancer Virology, Leeds Institute of Medical Research, University of Leeds, said:

“This pandemic agreement announced by the WHO is, in principle, a hugely positive advancement in planetary-wide pandemic preparedness and co-operation, which was found to be lacking on many fronts when SARS-CoV-2 first emerged in 2019.  Embedded throughout the text are recurring themes of equity, cooperation and preparation, which are all of vital importance.

“In addition, the importance of combatting mis/disinformation is highlighted, both of which have grown in their insidious influence since 2020, hampering our ability to deal effectively with both pandemic and other illnesses, exemplified by the dreadful measles outbreak in the USA at present.

“Notably, it involves the establishment of networks to help enable equitable access and support for all countries involved in the agreement.  The “Pathogen Access and Benefit Sharing System” (PABS) will allow access to both materials and information, notably sequencing data, in the event of an outbreak.  This will run in parallel with the Global Supply Chain and Logistics Network (GSCL), to promote equitable access to medical supplies and other items.  These will be overseen by the Intergovernmental Working Group (IGWG).

“All of these advances will be a huge benefit if and when they are implemented, but I think there are areas that need to be addressed in order to realise its potential impact, and these will require significant buy-in from world governments.  The first is that Governments must be made to recognise that pandemic preparedness is not something that is only needed once a century, and cannot simply be kicked into the long grass.  This is challenging given the current geopolitical landscape, which is ravaged by conflict, inequity, and full-blooded attacks upon public health and scientific research in certain countries where they were previously world-class.  We must not allow the lack of institutional memory that plagued the UK pandemic response, for example, where learnings from our own preparedness exercises, scientific advisors, and other countries were simply not recognised or acted upon by the sitting Government.  This includes the importance of Find, Test, Trace, Isolate, and support (FTTIS), so brilliantly implemented in certain South East Asian countries and at the heart of WHO pandemic response guidance.  It also involves adopting the “precautionary principle” and the importance of a multi-layered response to disease outbreaks recognising the dangers of both airborne and pre/asymptomatic transmission.

“The second area is the need for Government buy-in to either incentivise and influence, or potentially replace the current model where development of vaccines and therapeutics are almost entirely dependent upon large Pharmaceutical Companies.  Pharma cannot be blamed for seeking a return on its considerable investments running into the billions of dollars; they are, after all, businesses.  So, persuading them to support development of medicines that may or may not be used in the immediate future is understandably difficult.  This also generates a catch 22 scenario due to the associated emphasis placed upon “marketability” for the few Government funded research schemes that include emerging/re-emerging pathogens in their remit.  The principle of the 100 day plan is an excellent one, namely developing core medical resources targeting high risk pathogens that can be rapidly adapted to specific agents.  However, this is again entirely dependent upon more Government support to reach this state of readiness in a meaningful sense.

“Both of these issues naturally involve investment at a time when many nations face a cost-of-living crisis, but their potential value in preventing the trillions of dollars that the COVID pandemic continues to cost the world is incalculable.  I hope that this WHO agreement can become a vehicle by which Governments genuinely unite and achieve a genuine state of readiness, especially as many virologists are genuinely concerned about the risks of the ongoing avian influenza panzootic (animal pandemic).”

Prof Sir Andrew Pollard, Director of the Oxford Vaccine Group; and Ashall Professor of Infection and Immunity at the Pandemic Sciences Institute, University of Oxford, said:

“The pandemic agreement is an important endorsement of a globally collegiate approach to tackling the existential threat we face from a future pandemic.  It recognises the particular challenges highlighted by the COVID19 pandemic around equity in access to life saving vaccines and drugs, the geographical boundaries caused by limited global manufacturing capability and nationalism.  The agreement also highlights the importance of international research coordination so that we are better prepared for the next one.  It shows a level of cooperation and coordination that could make the world a safer place, but the real test of such a document is in its execution.  It is heavily dependent on the actions of the world’s major powers today to lay the groundwork in surveillance, strengthening of health systems distributed manufacturing and research, all of which are severely hampered by the current political and economic headwinds.  We will also critically need such cooperation to remain strong in the face of the next life-threatening microbial invasion of national borders, which will challenge even the most resolute political minds.”

Prof Mishal Khan, Professor of Global Public Health, London School of Hygiene & Tropical Medicine, said:

“It’s been a huge challenge to get to this point so the fact that this has now been formally agreed at the World Health Assembly, is very welcome.

“But in reality we won’t know how useful this agreement is until the next pandemic hits.

“A key question is around whether countries will voluntarily comply with the terms and, if not, how enforceable is it.  Past experience, for example with the International Health Regulations, suggests that powers to enforce will be limited.

“The success of this treaty will also depend on each country’s capacity to contribute to potentially valuable elements such as the Pathogen Access and Benefit-Sharing System through collecting and sharing high-quality data.

“It’s concerning that the US will not be bound to the treaty and has not been part of the final discussions, leaving us unsure what its approach to resource and data sharing will be in future disease outbreaks.

“We must continue to strengthen and support capacity globally to ensure the agreement is equitable and has the best chance of being effective in protecting the world from pandemics.”

Prof Alice Norton, Associate Professor, Pandemic Sciences Institute, University of Oxford, said:

“The adoption of the Pandemic Agreement by the 78th World Health Assembly today is welcome news for global health security.

“Article 9 on research and development was one of the first to be unanimously agreed by member state negotiators.  This recognises the ability for science to get us out of a pandemic, as was the case for COVID-19, showing that unlike many other natural disasters we can mitigate the risks and impacts of pandemics through science.

“Respect for human rights, equity, solidarity and science-based evidence are all key principles rightly enshrined in the Agreement.

“What will be needed now is the political will and sustainable financing so that all countries can make the Agreement a reality.

“It is a mistake to believe that our recent experience of a pandemic means we are safe for a while.  The threat of epidemic and pandemic diseases that could devastate lives, livelihoods and economies still loom large.

“Recent global health funding cuts only serve to worsen our preparedness and response capabilities.  After today’s announcement, governments must now step-up and put the Agreement’s principles into practice.”

Prof Martin Antonio, Professor of Molecular Microbiology and Global Health based at the MRC Unit The Gambia at LSHTM, and Co-Director of the LSHTM Centre for Epidemic Preparedness and Response, said:

“Having all WHO member states (except the US) endorsing the treaty is a big leap forward in the fight against future pandemics.  Crucially it will accelerate appropriate action, for example the commitment we need to enable vaccines to be developed quickly and made globally accessible within the 100 days mission target set by CEPI.

“This is a global agreement and will only work with global support.  But to make these measures effective, we must also push for investment in regional measures such as the development of ‘pandemic’ manufacturing facilities in Africa in support of diagnostics, vaccines, and other interventions.”

Dr Richard Hatchett, CEO of CEPI, said:

“Rebecca Solnit once wrote that ‘Perfection is a stick with which to beat the possible.’  Is the Pandemic Agreement perfect?  No.  But no such international agreement can be.

“Does it represent a huge step forward, in terms of recognising the threat that pandemics pose and as a binding expression of solidarity against this common threat?  Absolutely.  It is now a defining feature of the landscape, under the canopy of which all our efforts going forward will be conducted.

“Is there a great deal of practical work still to be done to make the world safe from pandemics?  Of course.

“But this is a moment to celebrate!  And also a moment to rededicate ourselves to the hard work of pandemic prevention, preparedness, and response.”

CEPI statement on the adoption of the Pandemic Agreement: 

CEPI commends the commitment of countries and negotiators to advancing this once-in-a-generation opportunity to make the world a safer place.  By their nature, pandemics can only be effectively tackled through international cooperation and the adoption of the Pandemic Agreement represents an historic step forward in this regard.  It seeks to drive systemic change that will address the inequity that characterized the response to COVID-19 and brings us closer to realizing the 100 Days Mission goal to respond to future pandemic threats with a new vaccine in just three months.  

CEPI stands ready to support the implementation of the Pandemic Agreement, including: 

• Requirements for publicly-funded R&D to include equitable access obligations – such as affordable pricing terms, technology transfer, information sharing;

• Commitments to support sustainable and geographically distributed production facilities with the capability to scale up for rapid response in a health emergency;

• The establishment of a multilateral pathogen benefits sharing system that supports rapid and efficient sharing of samples and data on pathogens with pandemic potential to expedite R&D for medical countermeasures.  This, together with a global supply chain and logistics network, will help to strengthen research and innovation and support global access to medical countermeasures based on public health need rather than ability to pay.

While we celebrate today’s achievement, we must also recognise that the Agreement on its own will not deliver the level of pandemic preparedness the world urgently needs.

It will take sustained investment, enduring political commitment and unprecedented scientific collaboration to create the systemic change needed to protect not just our own generation, but generations to come.  

Dr Daniela Manno, Clinical Assistant Professor, London School of Hygiene & Tropical Medicine, said:

“We know pandemics do not respect borders.  COVID-19 demonstrated how quickly infectious diseases can spread and underscored the importance of international cooperation for early detection and response.

“Adopting this first global agreement on pandemic preparedness and response is a major milestone.  It signals a global commitment to avoiding the fragmented and unequal responses of past crises, and to promoting greater solidarity and equity in future health emergencies.

“It shows that countries are willing to work together more effectively and more fairly, through timely data sharing, coordinated rapid responses, and fair access to vaccines, diagnostics and treatments.

“However, while the treaty marks important progress, concerns remain about its strength and enforceability.  For example, the proposal to create a Coordinating Financial Mechanism is a positive step, but it lacks firm commitments to new, long-term funding streams, specifically for low- and middle-income countries.  Without clear financial provisions, LMICs may face increased debt or be forced to divert funding from other essential health services to meet treaty obligations.

“While the treaty references inclusiveness and community engagement, there needs to be a greater emphasis on integrating local knowledge and enabling community-led decision-making.  This is crucial to avoid top-down approaches that may not reflect the needs and realities of diverse communities, particularly in LMICs.”

Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:

“The WHO Pandemic Agreement is quite a triumph for diplomacy, and will rely hugely on cooperations from the member states.  The draft agreement is full of words such as equity, respect and solidarity.  This is where the WHO is very strong, in providing expert guidance from an ethical and practical standpoint that applies across the world.  However, the Organization does not have much of a role in any legal enforcement.

“The Agreement makes reference to the International Health Regulations (IHR) 2005.  Member states have a legal obligation to adhere to the IHR, although it’s not fully clear what would happen if a country chooses not to.

“For example, the USA are technically still a member of WHO, with a one year notice period for withdrawal put forward by the Trump government.  Given their recent commentary on national and global health, one can imagine they may not comply with regulations both currently in place and proposed here under the Agreement.”

https://apps.who.int/gb/ebwha/pdf_files/WHA78/A78_10-en.pdf

https://www.who.int/news/item/19-05-2025-member-states-approve-who-pandemic-agreement-in-world-health-assembly-committee–paving-way-for-its-formal-adoption

https://www.who.int/news/item/20-05-2025-world-health-assembly-adopts-historic-pandemic-agreement-to-make-the-world-more-equitable-and-safer-from-future-pandemics

Declared interests

Prof Alice Hughes: “None.”

Jeremy Knox: “No COIs.”

Prof Stephen Griffin: “Co-Chair of Independent SAGE.”

Prof Sir Andrew Pollard: “Professor Pollard is chair of JCVI which provides independent scientific advice on vaccines to DHSC.  The comment above is given in a personal capacity.”

Prof Mishal Khan: “No conflicts.”

Prof Alice Norton: “Professor Alice Norton receives a research grant from the World Health Organization – this does not relate to the Pandemic Agreement.”

Prof Martin Antonio: “I have no conflict of interest to declare.”

Dr Richard Hatchett: “No conflicts of interest to declare.”

Dr Daniela Manno: “No conflicts to declare.”

Dr Michael Head: “No COI from me (and not involved in the Pandemic Treaty in any way).”

For all other experts, no reply to our request for DOIs was received.

Scientists comment on an atypical case of BSE (Bovine Spongiform Encephalopathy) detected on a farm in Essex. 

Prof Ian Jones, Professor of Virology, University of Reading, said:

“The focus in this news release should be the word “atypical”, in other words this is not a case that signals the BSE of the 1980s has returned, but a rare incident not dissimilar to the rare cases of Creutzfeldt–Jakob disease in the human population. BSE is part of a group of diseases known as protein folding disorders and occurs naturally at very low levels. Only if material from a BSE case was to be recycled through a herd would there be any risk of higher numbers. In this case the animal has been destroyed so that particular risk, and any concern about onward transmission, has been entirely removed. 

Dr Barry Bradford, Lecturer, Mucosal Host Pathogen Interactions & Prion Research and Neuropathology Groups, The Roslin Institute, University of Edinburgh, said:

What is an atypical case of BSE, how often do they occur, and how do they differ from typical BSE cases?

“Atypical BSE is a form of prion disease that occurs spontaneously in elderly cattle. Similar to sporadic Creutzfeldt-Jakobs disease in humans which occurs with an incidence of around 1 case per million of the population and then only in people aged at least over 40 years old and more commonly over 60 years old. There is no known cause and both conditions display a forebrain dominant targeting of pathological changes which spread backwards through the brain. This is in contrast to infectious prion diseases such as classical BSE, typically acquired through exposure of contaminated food and affects younger cattle. Infectious prion disease leave a tell-tale trace through the gut,  immune organs, nervous connections, and ultimately it’s final destination spreading from the spinal cord forwards through the brain leaving much of this material infectious in its wake. Atypical or sporadic prion diseases rarely show evidence of prions outside of the brain. Experimental transmission to laboratory mice reveals classical BSE is highly infectious whilst atypical forms are difficult to transmit unless very specific conditions are met.

Where could this case of BSE have originated from/how was it detected?

“Sporadic/atypical cases are thought to arise naturally. Prions are a misfolded form of a host cellular protein normally present at high levels in the brain. Infectious prions are capable of inducing the refolding of the benign host protein into the infectious form very efficiently. It is hypothesized that chance misfolding events may occur naturally and eventually may overcome the host cells protein quality control mechanisms especially if these have deteriorated with age for example.

“This case will have been detected by the routine screening for BSE setup following the BSE epidemic. Cases may be identified by their clinical symptoms of prion disease detected by stockmen, farmers or veterinarians. Suspect cases are subject to testing for abnormal prion proteins. These tests may also highlight biochemical differences between atypical and classical prions such as the relative size of the misfolded protein, structural differences or as mentioned above relative presence or absence in specific brain areas. These methods are effective at correctly identifying classical vs atypical cases.

Should we be concerned that more cases will crop up?

“No, it is likely with the size of UK cattle population and our effective screening and control measures that further cases will be detected with a similar low incidence in aged cattle similar to sCJD incidence in humans. There is no evidence that atypical BSE is infectious or will spread within herds. What is important is that current effective surveillance continues to ensure that any future BSE cases are identified and dealt with appropriately. We still don’t know the exact source of classical BSE which resulted in the UK epidemic and one possibility is that it arose spontaneously in cattle similar to this case. Whilst the conditions that led to the BSE epidemic have been removed (i.e. recycling of animal protein via meat and bone meal) there are other forms of prion disease such as Chronic Wasting disease in deer that are naturally highly infectious within herds as well as spread via environmental contamination with prions. Therefore continued vigilance regarding prion diseases is imperative.

Do these cases pose a risk to human health?

“Due to the rarity of these cases and effective surveillance it is unlikely that atypical BSE poses a direct risk to human health. Atypical BSE is not considered infectious. Identified cases do not enter the food chain. Current legislation such as the bovine offal order also require removal of all high risk materials such as brain from all cattle entering the human and animal food chains.

How are these cases handed and what do we prevent more in the future?

“Effective surveillance, reporting and research should continue as it is impossible to prevent future (though) rare occurrences of spontaneous prion disease.”

Prof Neil Mabbott, Personal Chair in Immunopathology and Head of Immunology Division, The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, said:

“Atypical BSE (bovine spongiform encephalopathy) is a rare disease of cattle.  The disease is considered to occur sporadically and it is not acquired between cattle as an infection.  Atypical BSE differs from the classical BSE which caused the outbreak in the UK cattle herd in the 1980s and 1990s.  Classical BSE was considered by scientists to be spread amongst cattle through use of feed BSE-contaminated (meat and bone meal), and is estimated to have caused infection in up to half a million cattle during that period. 

“Very occasionally, rare atypical cases of BSE are sporadically detected in cattle, but these are considered non-contagious and are not linked to an infectious origin.  Four cases of atypical BSE have been detected in the UK in the past ten years.  This current case was detected through the routine surveillance and testing brain tissues from fallen stock animals. 

“The detection of this isolated case of atypical BSE shows that the UK’s surveillance programme is working well. There is no risk to the public, as the animal’s carcass will have been destroyed and no tissues will have entered the food chain. 

“BSE is a devastating neurological disease in cattle affecting the brain, spinal cord and some other organs.  Control measures remain in place to exclude these organs from the food chain to prevent the spread of BSE amongst cattle and to humans.  A measure of their success, is that there have been no cases of variant CJD (linked to consumption of BSE infected food) in people born after these controls were put in place in the UK in the 1990s.”

Declared interests

Dr Barry Bradford: Current COI “Lecturer at The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh. Funded by UKRI via BBSRC. Member of the British Neuroscience Association. Member and local representative for Prospect trade union. Reviewer Board member for International Journal of Molecular Sciences since 2021. Ad-hoc reviewer for numerous scientific journals.” Historic COI “Previously employed at The Institute for Animal Health by BBSRC. Previously part-funded by grants from Medical Research Council, Department of Health, Department for Environment, Food and Rural Affairs & Ministry for Agriculture Fisheries and Food. Member of the Society for Neuroscience/ Member of the British Society for Immunology. Member of the European Macrophage and Dendritic cell Society”

Prof Ian Jones: “I state no conflicts”

Prof Neil Mabbott: “I have no conflicts of interest to declare”

Scientists comment on the first detection of West Nile virus in UK mosquitoes, announced by the UK Health Security Agency. 

Professor Paul Long, microbiologist at King’s College London, said:

“Although virus-infected mosquitos have been found in the UK there’s no evidence yet that these mosquitoes will survive in the UK climate, although prolonged warm weather does increase the chances.”

Prof Tom Solomon, CBE director of the NIHR Health Protection Research Unit on Emerging Infections and of the Pandemic Institute in Liverpool said:

“The detection of West Nile virus in UK mosquitoes is a significant finding, especially as our climate changes. The virus is transmitted among birds by mosquitoes, and humans become infected when they are coincidentally bitten by an infected mosquito. It is most likely the virus arrived in the UK via an infected migrating bird. Climate change impacts on numbers and types of mosquitoes and allows emerging viruses to become established, and we are likely to see more of this, and similar viruses in the future.

“West Nile virus mostly causes just a febrile illness in humans, and can infect people with no symptoms at all. However, in a small proportion of patients the virus can cause neurological disease, which may lead to paralysis or even death. Unfortunately, there is no specific treatment. There have been no human cases so far, caused by virus transmitted in the UK, as far as we are aware. (We have had a handful of cases of West Nile virus among returning travellers). However, scientists, including those in our teams, are looking for evidence of unknown infection in humans. It is also important that doctors are aware that the virus is here in the UK, so that they can send samples from patients with brain infections of unknown cause.

“Given this is just a few infected mosquitos, the risk to the public is low. However, it underscores the need for surveillance for these kinds of pathogens, and funding for research to develop the diagnostic tests, treatments and vaccines that may ultimately be needed, the kind of work we are doing at the NIHR Health Protection Research Unit on Emerging and Zoonotic Infections and at The Pandemic Institute in Liverpool.”

Felipe Colón, Technology Lead in Data for Science and Health at Wellcome, said:

“Climate change isn’t just a future threat; it’s already reshaping disease patterns. As the climate continues to warm and rainfall patterns shift, the risk of diseases such as West Nile Virus spreading to Europe has significantly increased. This is not a new phenomenon, Europe has become increasingly more hospitable for West Nile Virus since the 1980s, with a period of rapid warming creating the perfect conditions for the virus to spread. Countries like the UK that were once considered low risk are now more vulnerable to outbreaks – a concern only amplified by the fact that there are currently no approved treatments for West Nile Virus.

“This case demonstrates the importance of good disease surveillance systems to monitor the risk and incidence of infectious diseases, especially those impacted by climate change. Thanks to the UK’s surveillance network and this research programme, the UK’s healthcare network will have a heightened awareness for potential human cases, increasing understanding of how this might have come about and enhancing our ability to treat any cases earlier and fully determine the risk to the UK population.”

Prof Lance Turtle, Chair in Immunity and Infectious Diseases, University of Liverpool, said:

What is West Nile virus and how dangerous is it to humans?

“West Nile virus is a mosquito transmitted virus that was first discovered in West Nile district of Uganda. The natural host is birds and it is spread between them by mosquitoes. Humans and horses can also be infected by the virus. If the virus infects humans, in most cases nothing will happen (in 8 out of 10 cases roughly). A small number of people, about 2 out of 10, get sick with a fever. A very small number, probably about between 1 in 100 and 1 in 200 get a more severe illness where the virus gets into the brain. This is a serious disease which can be fatal or do permanent brain damage in some cases. There are no effective treatments known, and no vaccine. There have been no cases of West Nile virus infection in humans acquired in the UK to my knowledge. There have been some cases that have occurred in travelers who became infected overseas and brought the illness back to the UK.”

Does this mean that the West Nile virus in these mosquitoes can transmit the disease to humans?

“This finding suggests that West Nile virus might be in the UK. It isn’t conclusive. The press release doesn’t give a lot of detail on exactly what the findings are, but it suggests that part of the genetic information of the virus has been found. This isn’t the same as finding the whole virus, which would give us more confidence that the virus is in the UK. But it is suggestive. There are other possibilities, like parts of another related virus have been misidentified. There’s another related virus that we know is in the UK called Usutu virus, but the title of the press release suggests the team are confident that this is indeed West Nile virus – there’s no reason to think they might be wrong.

“I don’t know much about this particular mosquito species, Aedes vexans. It’s not the typical mosquito that we would associate with West Nile virus transmission, at least not to people. The risk to humans is hard to quantify exactly but will be very low at the present time. The risk from West Nile due to travel is much greater. It’s found in many places – parts of Europe, especially Romania, East Africa, Israel, the USA, India etc.”

“There is no evidence to my knowledge that there is any transmission in the UK. This finding does not suggest that.”

How could the virus have got here inside the mosquito? The mosquito itself? Or via the infected horse?

“Most likely in one of two ways – it came inside a mosquito, or in a bird. There’s no reason to think it is in a horse.”

How worrying is this development for the public?

“This is certainly a bit worrying, that’s why UK HSA have a surveillance program to look for it. We have been expecting something like this for a while – there have been cases of West Nile in nearby countries like the Netherlands, for example, in 2020. However at the moment I think the risk is low and we do not need to be unduly worried – just aware. We can detect humans cases by laboratory testing, either of people who have the right kind of illness, or by looking at large scale for antibodies in blood. Some of this work is already being done in the UK. We are also on the lookout for cases of disease like this through the NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, which works in partnership with UK-HSA.”

Does this necessarily mean that we’ll start more mosquitoes in the UK with West Nile Virus?

“That’s hard to say. This could be a one-off, or it could be the start of a more sustained presence of West Nile in the UK. With warming temperatures, and given that West Nile is in other countries close by, we may end with the virus establishing itself in the UK. In similar countries like the Netherlands the number of cases in humans has been very small, so the risk to humans remains low.”

Prof Steven Sinkins, Professor at Centre for Virus Research, university of Glasgow, said:

What is West Nile virus and how dangerous is it to humans?

“West Nile virus is a member of the flavivirus group related to Japanese Encephalitis virus, and also dengue, Zika and yellow fever viruses, all of which are mosquito-borne. Most human cases have no symptoms or cause a mild fever, but especially in older people it can sometimes progress to infection of the brain and surrounding tissues or spinal cord (encephalitis / meningitis), and this can be fatal or lead to paralysis. Treatment is supportive only. There have been no known UK-acquired cases to date.”

Does this mean that the West Nile virus in these mosquitoes can transmit the disease to humans?

“Not necessarily – the virus needs to be able to make it to the mosquito saliva to be transmitted, and this has not been shown here.”

How could the virus have got here inside the mosquito? The mosquito itself? Or via the infected horse?

“West Nile virus most commonly circulates among birds, so migratory birds are the most likely source.”

How worrying is this development for the public? Should we be concerned about this? How easily can we detect potential future cases?

“It is definitely not a cause for alarm, but does warrant increased surveillance and potentially planning for increased mosquito control.”

Does this necessarily mean that we’ll start more mosquitoes in the UK with West Nile Virus?

“It is too early to say. West Nile virus did spread quickly across the USA after it was first introduced in 1999, but their climate is warmer and there are far higher numbers of susceptible mosquitoes.”

Prof James Wood, Infectious Disease Epidemiologist at the University of Cambridge and Co-Director of Cambridge Infectious Diseases, University of Cambridge, said:

“It is very interesting that UKHSA and APHA have published evidence of WNV infection in mosquitoes in England, although it is not especially surprising as it has been known for some time that previously infected migratory bird species have been travelling to and in some cases then spending summers in the UK. WNV has become more prominent across Europe over the last 10-20 years. Risk mapping has identified parts of England, in particular in the South, as sites where WNV transmission might be expected. It is not clear whether this finding is simply a new observation of something that has been occurring for years, or a new occurrence. APHA has monitored dead birds for WNV for some time, but not detected it and while this surveillance is to be applauded, surveillance in healthy wild birds has never been undertaken. Flaviruses such as WNV, more generally often do not cause disease in their avian hosts. The natural cycle for transmission for many of these does not involve mammalian hosts, but spillover into horses and humans, with clinical disease consequences is known as a concern for WNV when it does happen. Encephalitis is seen occasionally in both humans and horses.

“Veterinary and public health authorities have known for some time about the risks of WNV transmitting to humans and horses and this new finding does emphasise the importance of medical and veterinary surveillance in cases of unexplained encephalitis. When WNV is known to be circulating locally, then enhanced mosquito avoidance approaches (stabling of horses, especially at dawn and dusk in high risk areas) may be warranted.”

Dr Robert Jones, Assistant Professor at the London School of Hygiene & Tropical Medicine, said:

“There is currently no evidence that these fragments of genetic material are linked to any human cases of West Nile virus infection.

“However, this remains a significant finding by the Vector-Borne RADAR team and highlights the importance of continued mosquito surveillance across the country. If a mosquito acquires the virus and is a competent vector, it may transmit the virus to other individuals, some of whom may go on to develop the disease. Most West Nile virus infections are asymptomatic.

“The mosquito could have acquired the virus by feeding on an infected bird. It is possible that a bird became infected in another part of the world and then returned to the UK carrying the virus. While some birds show signs of infection, many species can carry West Nile virus without appearing to have an illness.

“Similarly, humans occasionally return to the UK from abroad carrying arboviral infections. However, this rarely leads to local transmission, either because our local mosquito species are not competent vectors, or because the chances of a mosquito acquiring the virus and passing it on are very low.

“As the UKHSA has outlined, the risk of West Nile virus to the UK population remains very low. However, due to climate change and the movement of people and goods, we are seeing a general expansion of mosquito-borne diseases into regions not previously associated with these infections—and that trend is expected to continue. Ongoing surveillance is essential to ensure that any future infections are detected early.”

Prof Heather Ferguson, Professor of Infectious Disease Ecology at the University of Glasgow, who leads the Mosquito Scotland project, said:

“This finding highlights the critical importance of having robust surveillance programmes in place to enable detection of the arrival, and later establishment, of new pathogens in the UK.  We have known for some time that climate and associated environmental changes are driving the expansion of mosquito vector species, and enhancing the probability of pathogen transmission. While the UK is still considered low risk for transmission of most mosquito-borne diseases of humans, this first detection of West Nile Virus in British mosquitoes is in line with predictions of how climate is increasing the likelihood of transmission.

“West Nile a zoonotic virus that mainly spreads between bird species, but can occasionally spillover into humans and horses if they are bitten by an infected mosquito. The majority of infections  in humans are asymptomatic (80%) or cause only very mild, flu-like symptoms that pass quickly.  However, in a very small proportion of cases (less than 1%) – usually in older people or those with compromised immune systems – symptoms can be more severe including encephalitis or meningitis, and in very extreme cases can cause death.  However, even with the finding of West Nile Virus fragments in mosquitoes in the UK, the risk of any infection in humans is considered extremely low at present, and even lower for severe infections.

“While many people consider the risk from mosquito-borne diseases arising only from the invasion of ‘tropical’ mosquito species into the UK, this is not the case.  Although the mosquito species in which West Nile Virus has been found in the UK is not currently widespread, several mosquito species native to the UK are also known to be capable for transmitting the virus, but do not do so at present because the environmental conditions, including temperature, are not favourable for transmission.  This could change in the future, which is all the more reason why we need surveillance, such as the invaluable programme that is being carried out by UKHSA which has led to this discovery.  Without these programmes, there would be no way to track and respond to these potential risks before they take hold.”

Prof Martin Hibberd, Professor of Emerging Infectious Disease at the London School of Hygiene & Tropical Medicine, said:

“I’m pleased to see that a UKHSA research surveillance is in operation and is able to give us this early warning of a potential health threat from West Nile Virus.

“This is a timely reminder of the importance of funding health and disease research, and I hope that these findings will lead to more extensive surveillance, to give a clearer picture of the scale of the problem.

“With the likely arrival of West Nile Virus into the UK, we also need to be prepared for the potential arrival of other viruses from the Flaviviridae family, such as the viruses that cause dengue.

“However, detecting these viruses in mosquitos does not mean that they are able to effectively transmit the virus to cause outbreaks. More work needs to be done to assess the likely chances of these mosquitos passing the virus to humans, which is known to be reduced in cooler climates, such as the UK, compared to the tropical environments these viruses usually circulate in.

“This research and surveillance should become part of a heightened preparedness to combat the effects of climate change.”

Dr Ilaria Dorigatti, Senior Lecturer, Imperial College London, and Dr Rebecca Christofferson, Associate Professor in the Department of Pathobiological Sciences, LSU School of Veterinary Medicine, both said:

“West Nile Virus is a zoonotic flavivirus that circulates in a bird-to-mosquito and mosquito-to-bird cycle and occasionally spills over into the human population, with sporadic cases in horses. Both humans and horses are considered “dead end” hosts, which means humans and horses can acquire the virus when bitten by an infectious mosquito but cannot transmit the virus back to mosquitoes. Most human infections may develop a self-limiting febrile illness that resolves without any treatment, but a small proportion of infections develops severe neurological conditions that require hospitalisation. Older age is associated with a higher risk of developing and reporting severe disease. The same pattern is seen in horses where severe neurological symptoms can occur. In horses, unlike people, there is a licensed vaccine (Equilis West Nile).

“The virus circulates endemically across several countries in Europe, where transmission is seasonal and lasts between April and October. In Europe, cases of West Nile are reported through the European Surveillance System TESSy with over 1400 human cases documented in 2024. Across Europe, nearly 500 cases of equid infection were reported in 2024. To date, no locally acquired human cases of West Nile virus has been detected in the UK, all cases reported in the UK were acquired when travelling abroad.

“Importantly, there are mosquitoes in the UK that are capable of transmitting WNV. Aedes vexans (the mosquito that has been detected positive) bite a wide array of animals, including birds and mammals, primarily at dusk. Culex pipiens also bite preferentially in the evening hours and twilight. Another mosquito that has been transiently detected in the UK, Aedes albopictus, can also carry WNV and bites during the day, most often at dawn and dusk.

“The risk to the human population remains low, and early detection in mosquito pools points to the success of UK vector surveillance programmes. However, the detection of WNV in UK mosquito populations does call for heightened awareness. This also demonstrates a need for strengthening surveillance as changing climate make conditions more suitable for the mosquitoes to live longer, be in contact with people more, and transmit the viruses they carry.”

Prof Matthew Baylis, Oxenhale Chair of Veterinary Epidemiology, University of Liverpool, said:

“West Nile virus is related to dengue virus, yellow fever virus, Zika virus and tick-borne encephalitis virus. West Nile virus is transmitted by mosquitoes between birds.  It can cause disease, and sometimes severe disease in people and horses, with occasional fatality. Generally, about eighty percent of infected people are asymptomatic; twenty percent suffer fever, achiness, tiredness and other fairly mild symptoms; but one percent can develop encephalitis, which is sometimes fatal.

“Antibodies to West Nile virus have previously been reported in birds in the UK; and now the virus has been detected in mosquitoes. West Nile has never been transmitted to people in the UK.

“It is possible that the virus entered the UK in mosquitoes, perhaps carried to the UK on winds, or hitching a ride in a plane, train or automobile. But it is much more likely that it was brought in by a migratory bird, which was then fed upon by mosquitoes. Humans and horses do not develop sufficient viraemia (i.e. concentration of virus in blood) to infect mosquitoes so they are unlikely to be the source.

“This should not be a major cause of concern: the spread of West Nile from southern Europe to northern Europe in the last few years has not led to a significant public health issue, although there have been cases in both humans and horses. I will not be surprised if we see a few cases in the UK too. There is a need to heighten surveillance, in humans, birds and mosquitoes.  This is especially important given that severe cases that report or are reported to medical or veterinary authorities tend to be the tip of the iceberg, with many infected people or horses carrying the virus but not showing symptoms or signs.”

Dr Steven White, Theoretical Ecologist, UK Centre for Ecology & Hydrology (UKCEH), said:

“West Nile virus is a virus that is usually transmitted by Culex mosquitoes. The primary hosts are birds which can pass on the virus to feeding female mosquitoes that need the bird blood for their reproduction cycle.

“Humans and horses can also become infected if they are fed on by an infected mosquito, but once a human or horse becomes infected the virus cannot be passed on, unlike viruses such as dengue and chikungunya. Thus, humans and horses are known as dead-end hosts. However, the virus can cause West Nile fever in humans, which is mostly mild, but can cause a fever, vomiting, a headache or rash, with only a small fraction of people developing more severe symptoms.  

“Not only are birds important in the transmission cycle of West Nile virus, but they are also important for its spread. Birds pose the most likely route of the virus’s introduction into the UK, whereby a migratory bird is infected somewhere in continental Europe where the virus has established (e.g. France, Italy, Spain, Germany) and flown to the UK, then mosquitoes feed on the bird.

“The risk to the human population remains low, however, as this is the first time that West Nile virus has been detected in the UK ecosystem, we must remain vigilant. Our research shows that climate change is likely to increase the risk in the UK as suitability for our native mosquitoes and viral replication increases*. Thus, it is possible that in the near future that West Nile virus could establish in our bird population which then increases the risk to humans and horses.”

* Paper – https://doi.org/10.1098/rsif.2021.0049

Prof Grant Hughes, Department of Vector Biology at Liverpool School of Tropical Medicine, said:

What is West Nile virus and how dangerous is it to humans?

“West Nile virus is a flaviviruses transmitted mainly between birds and mosquitoes, but occasionally mosquitoes will feed on other vertebrates including humans which can lead to virus infections. Symptoms in humans include fever, head and body aches, flu-like symptoms and in rare occasions the virus can infect the nervous system which leads to further complications. In horses there is a vaccine. This is the first detection of WNV in the UK, but other similar viruses such as Usutu virus have been identified in birds.”

Does this mean that the West Nile virus in these mosquitoes can transmit the disease to humans?

“It appears PCR has been used to find the virus in these mosquito pools, but it is not known if these mosquitoes can transmit. Other studies have shown that this mosquito species is a competent vector for this virus. Culex mosquitoes in the UK will also likely be able to transmit this virus to humans.”

How could the virus have got here inside the mosquito? The mosquito itself? Or via the infected horse?

“The virus potentially entered the UK via migratory birds.”

How worrying is this development for the public?

“If we look at Europe we can see West Nile virus and Usutu viruses’ cases expanding to new territories as mosquitoes expand their geographic range. Dengue transmission has recently been seen in Paris. Given that there are mosquitoes in the UK that can transmit these viruses it will be likely that additional transmission events will occur in the future. Further surveillance of mosquito and bird populations will be important for monitoring the virus in the UK and evaluating the risk of virus transmission to humans over time.”

Does this necessarily mean that we’ll start more mosquitoes in the UK with West Nile Virus?

“The arrival of West Nile Virus into the UK was more of a “when” than an “if”. It will be likely that there will be future transmission event in the future.”

Any other useful information relevant to this situation.

“We are actively investigating Wolbachia [a native bacterium that lives within insects]-based control strategies that could be used to reduce mosquito numbers and/or stop mosquitoes transmitting viruses.”

Prof James Logan, Professor of Medical Entomology and Director of Arctech Innovation, London School of Hygiene & Tropical Medicine (LSHTM), said:

What is West Nile virus and how dangerous is it to humans?

“West Nile virus (WNV) is a mosquito-borne virus that affects birds, animals and humans. In most people it causes mild, flu-like symptoms or no symptoms at all — but in rare cases, it can lead to serious neurological illness, including encephalitis or meningitis. There is no specific treatment or vaccine for humans. While WNV has not previously circulated in the UK, its presence in parts of Europe has been growing for years, and its eventual appearance here was expected.”

Does this mean that the West Nile virus in these mosquitoes can transmit the disease to humans? Is there any evidence it has done already?

“If the mosquito is infected, then yes — it can transmit the virus to humans. But it’s important to stress: transmission requires a full local cycle involving infected birds and suitable mosquito species. As of now, there is no evidence of human infection acquired in the UK. However, the detection of the virus in mosquitoes marks a significant step in that direction.”

How could the virus have gotten here?

“The virus most likely arrived via an infected bird or mosquito — both can travel considerable distances, especially with seasonal migration. The infected horse cannot have passed the virus on; horses, like humans, are “dead-end” hosts, meaning they don’t contribute to the onward spread. The horse is a warning sign, not the source.”

How worrying is this development for the public?

“This development is serious, but it is not unexpected. It does not require public alarm, but it does call for vigilance and investment in long-term preparedness. Public health agencies and veterinary networks have surveillance systems in place, but as conditions change — with warmer weather, increased mosquito activity and shifting bird migration — we need to stay one step ahead. This is a moment to recognise that the UK is no longer immune to some diseases once considered ‘tropical’.”

Does this necessarily mean that we’ll start seeing more mosquitoes in the UK with West Nile Virus?

“Not necessarily — but the conditions that make it possible are here, and becoming more favourable. The detection of WNV in even a small number of local mosquitoes is a signal that the door is now open. Whether the virus takes hold will depend on a combination of environmental, biological and human factors — including how well we prepare.”

Any other useful information relevant to this situation.

“This is part of a broader trend we can no longer ignore. Climate change, global trade and travel, and changing ecosystems are bringing vector-borne diseases — like West Nile, dengue and others — closer to home. We are entering an era where we must learn to live smarter in a bug’s world. That means stronger surveillance, better public communication, and a public health system ready for the challenges ahead. This is not the beginning of a crisis, but it is a signpost to the future. How we respond now matters.”

Declared interests

Prof Grant Hughes: “I have an industry partnership with Google to develop Wolbachia based strategies for mosquito control suitable for use in the UK. This work is funded by the BBSRC.”

Prof James Logan: CEO of Arctech Innovation (declaration – we are an innovation companies making products that detect and protect against vector borne diseases).

Dr Steven White: No interests to declare.

Prof Matthew Baylis: I do not have any conflicts of interest relevant to this story.

Prof James Wood: Employed at the University of Cambridge and an officer of the British Equine Veterinary Association (BEVA).

Dr Ilaria Dorigatti and Dr Rebecca Christofferson: We have no competing interests to declare.

Prof Martin Hibberd: My research into disease prevention has been funded by a wide variety of sources over the years including pharmaceutical companies such as Roche, Novartis, and Johnson & Johnson.

Dr Robert Jones: I am employed by both LSHTM and Arctech Innovation.

I am a professor of immunity and infectious diseases at the University of Liverpool. I am a clinician as well as a researcher. I study mosquito borne virus infections, such as Japanese encephalitis which is a similar virus to West Nile virus. I work on a vaccine for Zika virus (another mosquito transmitted virus) and I am a joint patent holder on this vaccine. I am the lead investigator of the ARBO-UK study which is recruiting patients with illnesses like West Nile. I declare consulting fees from MHRA and Bavarian Nordic, and speakers’ fees from Eisai Ltd, Medscape, and the Primary Care Cardiovascular society. I declare consulting fees from Astrazeneca and Synairgen, paid to the University of Liverpool. I received travel and accommodation support for conference attendance (ECCMID) from AstraZeneca.

Professor Tom Solomon: Director of the NIHR Health Protection Research Unit on Emerging and Zoonotic Infections and of The Pandemic Institute in Liverpool. He was involved in the West Nile Virus outbreak in the USA in the late 1990s, and has been studying mosquito-borne viruses for 30 years.

Professor Paul Long: No conflicts.

For all other experts, no response to our request for DOIs was received.

Scientists comment on UKHSA announcing a rabies case in an individual that had contact with an animal in Morocco. 

Dr Chris Smith, Clinical Associate Professor, London School of Hygiene & Tropical Medicine (LSHTM), said:

“Rabies is a fatal but preventable disease. Although cases in UK travellers are very rare, this recent tragic case underscores the importance of awareness and timely treatment.

“Rabies is endemic in many parts of the world, including popular holiday destinations such as Morocco, Turkey, India, Thailand, the Philippines, and Indonesia. All human rabies cases reported in the UK since 1902 have been acquired abroad: typically through dog bites. Since 1946, 26 imported cases have been reported, with the most recent prior to this being in 2018, following a bite from a cat in Morocco.

“Travellers to countries where rabies is present should seek pre-travel advice regarding vaccination.

“Rabies is usually transmitted to humans through the bite or scratch of an infected animal, most often dogs, but also cats and bats. Even a minor scratch or lick on broken skin can pose a risk. If exposed, immediate first aid is essential: the wound should be thoroughly washed with soap and water, and prompt post-exposure prophylaxis (PEP) – including a course of rabies vaccinations and, in some cases, rabies immunoglobulin – should be sought. These interventions are highly effective when started early.”

“The key public health messages are:

• Rabies is a deadly but preventable disease
• Seek pre-travel advice regarding vaccination when visiting high-risk countries
• Avoid contact with animals abroad; if bitten or scratched, seek medical care immediately — don’t wait for symptoms to appear”

Further information

https://www.gov.uk/guidance/rabies-epidemiology-transmission-and-prevention

https://www.gov.uk/government/publications/rabies-risks-by-country/rabies-risks-in-terrestrial-animals-by-country

Declared interests

Dr Chris Smith: No conflicts to declare.

A study published in NPJ Vaccines looks at adjuvants in vaccines and their association with a lower risk of dementia. 

Dr Julia Dudley, Head of Research at Alzheimer’s Research UK, said:

“Dementia is not an inevitable part of ageing. Identifying ways to reduce dementia risk is a priority for research, and vaccination offers an intriguing area of exploration. There have been an increasing number of studies suggesting a link between people who receive certain vaccinations, like the Shingrix vaccine, and a decreased risk of dementia. This study offers a potentially different perspective on what might be linked to this finding.

“In this latest large US-based observational study, researchers are proposing that it might be the adjuvant that is providing a protective effect, rather than the disease the vaccine is seeking to protect against. This study looked at dementia diagnoses in people who had received vaccines with the AS01 adjuvant and those who had a flu vaccine, which doesn’t contain this component.

“An adjuvant is a substance in the vaccine used to create a boosted immune response, designed to give more effective protection upon exposure to the virus.AS01 is in the shingles vaccine Shingrix, and Arexvy, the vaccine to protect against respiratory syncytial virus (RSV).

“They found people who had Shingrix, Arexvy or both of these vaccines were less likely to get a dementia diagnosis within 18 months. They found no difference between the Shingrix or Arexvy in terms of reducing dementia risk.

“One of the strengths of the study is that it adjusted for factors that could influence risk, such as underlying health conditions and some lifestyle and environmental factors. However, as the study is observational and examined past health data, the researchers cannot conclude how the Shingrix and Arexvy vaccines may protect against dementia. We also cannot rule out that the link between vaccine and dementia risk is due to other factors not captured in this study, such as social and lifestyle factors.

“One of the limitations highlighted by the authors was around people not having a dementia diagnosis when they could be living with the condition, which could skew the findings. We do not know if the adjuvant is reducing the risk of dementia or delaying its onset. The follow-up period was only 18 months, so more research is needed to determine the potential long-term effects of the vaccines.

“As we understand more about the biological mechanisms behind any protective effects seen with vaccines, we may be able to investigate new treatment approaches.”

Prof Kevin McConway, Emeritus Professor of Applied Statistics, Open University, said:

“This is an interesting, worthwhile and statistically competent piece of work, but a lot more research needs to be done to make good sense of its possible implications for health care. In fact it’s a good example of how scientific and medical knowledge has to be built up through a series of studies, not just a single piece of work.

“Previous research has provided pretty convincing evidence that vaccination against shingles, in older people, can reduce dementia risk. A recent study (published 2024), by the same research team responsible for the new study, found that the reduction in dementia risk is greater in people who had the shingles vaccine now in most widespread use, including in the UK (it’s called Shingrix), than with the previous vaccine (Zostavax).

“However, that study could not provide direct evidence on the reason for the risk difference between the two shingles vaccines. One possibility is that having shingles might increase dementia risk, and that the new vaccine provides better protection against shingles than the old one did, so reducing dementia risk. Another is that there’s some component in the new vaccine that reduces dementia risk. Or it could be some combination of these possibilities.

“The new Shingrix vaccine differs from the old Zostavax vaccine in several ways, but one difference is Shingrix vaccine contain a substance called AS01, while Zostavax does not. Some previous research has indicated that it’s possible that AS01 somehow provides in itself a reduction in dementia risk. AS01 is not the ingredient of the vaccine that directly incites the immune system to develop immunity against shingles. Instead it is an adjuvant – a substance that is intended to help the immune system to respond to the vaccination. 

“AS01 is also used as an adjuvant in another vaccination offered to older people; the vaccination against the respiratory virus infection RSV (respiratory syncytial virus), which is now recommended for people in the UK aged 75-79.  One of the vaccines in use against RSV also contains AS01. (There’s another available vaccine that does not contain it.) So the research team responsible for the new study used data from a large set of American electronic health records, to compare dementia risk over a period of 18 months after vaccination for older people who had had various different vaccinations containing AS01 (just the RSV vaccine, just the shingles vaccine, or both). These people were compared with older people who had had a flu vaccine, not containing AS01.

“The researchers found that those who had had either of the two AS01-containing vaccines (against RSV or shingles) had a lower risk of being diagnosed with dementia in the 18 months after vaccination than those who had had the flu vaccine. This pattern of lower risk showed up in people who had had just one of the AS01 vaccines, or both, though there were some relatively small (and statistically uncertain) differences in the average size of the risk reduction, compared to the flu vaccine, for different groups.

“What’s still not known from this study is exactly why these risk differences occur. The researchers mention that, in some way, they could occur because having either RSV or shingles might in itself increase dementia risk, so that having a vaccine that makes it less likely to have one or both of those diseases might reduce dementia risk. Or it could be because of some protective effect of the AS01 adjuvant, which is in these vaccines but not in the flu vaccine. (Or some combination of these possible effects.)

“The researchers give some arguments why they feel AS01 itself is likely to play a protective role against dementia. I don’t have expertise in virology so can’t comment directly on those arguments. But it’s at least a possibility, from all the existing evidence, that AS01 could have a protective effect. This study also doesn’t provide direct evidence on how AS01 might work to reduce dementia risk, but the researchers give some suggestions based on other studies as to what could be happening. Again I can’t comment on those.

“It’s because of this inevitable lack of knowledge about exactly how AS01 might be involved in reducing dementia risk that the researchers are asking for more studies, some of them using other research methods, to find out more. I agree with this recommendation, because in my view the results of this study provide a clear justification for looking further. But we’re not yet anywhere near the stage of using the results of the new study to change clinical practice. Also, the new study can’t make the timescale of risk reduction very clear, because the follow-up period to look for dementia diagnoses was relatively short at 18 months.

“This was an observational study – the people weren’t assigned at random to receive a particular pattern of vaccinations, but just did what they would have done anyway in consultation with health professionals. In any observational study, there can be issues about what is causing what. The basic problem is that people who receive different vaccinations will also differ in terms of many other factors – age, sex, what diseases they have previously had or still have, and many more. Some of these factors may be potential confounders, as they are called – that is, there’s a possibility that they are the cause of differences in dementia risk, and not the actual vaccinations at all. 

“The researchers did a very thorough job of allowing for potential confounders, by doing something called propensity score matching. This involves setting up a statistical model that predicts people’s chances of having a dementia outcome, regardless of what vaccines they had had, and then matching people who (for example) had had the RSV vaccine but not the shingles vaccine with people who had had the flu vaccine. In this research the statistical model for the matching involves a very wide range of potential confounders. Then direct comparisons are based on these matched pairs of people. That means one can get a lot closer to comparing like with like groups, who don’t differ (on average) in terms of potential confounding factors.

“The process can’t entirely avoid the possibility that there are confounding factors that couldn’t be dealt with in this way, and that’s why the research paper says clearly that unmeasured confounding can’t be entirely ruled out. So there has to remain doubt about whether the risk differences are caused by the different vaccines. This is in addition to the inevitable doubts about which aspects of the vaccines (AS01 or something else as well) might be causes of the risk differences – if indeed it’s the vaccines that do turn out to cause the differences. These are yet more reasons why this research is nowhere near being the last word.”

Prof Sir Andrew Pollard FMedSci, Ashall Professor of Paediatric Infection and Immunity and Director of the Oxford Vaccine Group, University of Oxford, said:

“There are now a number of studies which have shown an association between shingles vaccination in older adults and a reduced rate of dementia in the vaccinated population. The fact that two different vaccine platforms (both live attenuated shingles vaccines and the adjuvanted shingles subcomponent vaccine) saw similar associations supported the idea that the mechanism was as a result of vaccine-prevention of reactivation of the usually dormant shingles virus in the brain. Another virus from the same family, herpes simplex virus (the cold sore virus) has also been associated with dementia raising the possibility that both of these viruses (shingles and herpes simplex) could cause infection, possibly silently and recurrently, in the brain that led eventually to dementia. Unfortunately, there is no licensed vaccine for herpes simplex at this time. However, this latest study published in npj vaccines shows that another vaccine, against the completely unrelated respiratory virus, RSV, is also associated with a reduced rate of dementia. The authors argue that this is because of a non-specific effect of these vaccines on the immune system which generates an environment in our bodies which is somehow protective against dementia, though further studies are needed to confirm this. Such a mechanism could account for the effects driven by both shingles and RSV vaccines. The various studies of the impact of vaccination on dementia are all observational studies which could have a risk of bias, as it can be challenging to adequately control for differences between those who seek vaccination and those who don’t, but the consistent finding across multiple studies makes the observation more convincing. It is premature to be too certain about the mechanism by which vaccines might reduce dementia risk, but these observations provide further incentive for those eligible to turn up for their scheduled vaccination visits to prevent the unpleasant and potentially serious and life-threatening infections for which they were designed, but with the added possible benefit of a longer dementia-free life-span. What’s not to like?”

‘Lower risk of dementia with AS01- adjuvanted vaccination against shingles and respiratory syncytial virus infections’ by Maxime Taquet et al. was published in npj vaccines at 10:00 UK time Wednesday June 25th 2025. 

DOI: 10.1038/s41541-025-01172-3

Declared interests

Prof Kevin McConway: No conflicts.

For all other experts, no reply to our request for DOIs was received.