#18,457
While no one can say with certainty what HPAI H5Nx will do next, its current trajectory - and recent successes in infecting new mammalian species - has many experts and long-time flu watchers more than a little concerned.
HPAI H5 is now credited with sparking the largest epizootic on record, has spread globally to nearly every corner of the globe, and continues to show signs of mammalian adaptation.
A few (of hundreds) of recent studies include:
Nature Reviews: The Threat of Avian Influenza H5N1 Looms Over Global Biodiversity
Travel Med. & Inf. Dis.: Pacific and Atlantic Sea Lion Mortality Caused by HPAI A(H5N1) in South America
EID Journal: Recent Changes in Patterns of Mammal Infection with Highly Pathogenic Avian Influenza A(H5N1) Virus Worldwide
Recently, we've also seen signs of growing antiviral resistance in some H5 viruses (see Emerg. Microbes & Inf: Oseltamivir Resistant H5N1 (Genotype D1.1) found On 8 Canadian Poultry Farms) and as Maggie Fox explained last year in SCI AM - A Bird Flu Vaccine Might Come Too Late to Save Us from H5N1, our pharmaceutical options during the opening months of any pandemic will be limited.
While none of this guarantees that HPAI H5 will spark the next pandemic, it is certainly at the top of our list of contenders. And while many recent cases have been mild, its history suggests it is capable of producing severe and fatal infections.
But the response of governments (both here in the U.S., and around the globe) has been largely to dismiss the threat as `low', and to treat H5 as more of an agricultural or economic concern than a public health threat.
Last month, in Nature: Lengthy Delays in H5N1 Genome Submissions to GISAID, we learned that the average delay for submitting non-human sequences was 7 months, and that Canada came in last at 20 months.
We continue to see diplomatically worded pleas to countries to share data (see WHO Guidance: Surveillance for Human Infections with Avian Influenza A(H5) Viruses), but our visibility of the global spread of the virus grows increasingly dim (see Flying Blind In The Viral Storm).
Yesterday The Lancet Regional Health - Americas published a viewpoint article penned by some of the most recognizable names in virology - all members of the Global Virus Network (GVN) - which outlines the growing threat, and calls for urgent, proactive measures to prevent widespread outbreaks.
This group makes specific recommendations in 10 areas.
- Enhanced Surveillance
- Faster Genomic Data Sharing
- Improved Farm Biosecurity
- Preparedness Plans for the Roll-Out of Tests
- Strengthening Public Health Infrastructure
- Investment in Phenotype Prediction from Genetic Data
- Investment in Rapid Vaccine Development
- Preparedness Plan for the Roll-Out of Vaccines and Therapeutics
- Preparedness Plan to Allow for Rapid Clinical Studies
- International Collaboration
First the link and some excerpts from the article (which you'll want to read in its entirety), followed by link and excerpts from the GVN press release. I'll have a bit more after the break.
Enhancing the response to avian influenza in the US and globally
Maggie L. Bartlett a b, Peter Palese c a, Meghan F. Davis b a, Sten H. Vermund a d, Christian Bréchot a d, Jared D. Evans e a, Lauren M. Sauer e a, Albert Osterhaus f a, Andrew Pekosz b a, Martha Nelson g a, Elyse Stachler h a, Florian Krammer i a, Gage Moreno h a, Gene Olinger j a, Marion Koopmans k a
Summary
The recent emergence of highly pathogenic H5N1 avian influenza virus infections in dairy cows and humans in the U.S. has raised alarms regarding the potential for a pandemic. Over 995 dairy cow herds and at least 70 humans have been affected, including cases of severe disease and the first reported H5N1-related death in the U.S. Sporadic human infections with no known contact with infected animals highlight the possibility of viral adaptation for efficient human-to-human transmission. Concurrently, the virus continues to circulate in wild birds, backyard flocks, and hunted migratory species, further amplifying the risk to humans and domestic animals.This article provides an overview of the current outbreak status, emphasizes the importance of robust surveillance systems to detect emerging strains with pandemic potential, and highlights risks to the U.S. dairy and poultry industries. Recommendations for risk mitigation include enhanced biosecurity measures, improved surveillance, decentralized testing, and targeted public health messaging.
The Global Virus Network calls for urgent, proactive measures to prevent widespread outbreaks, leveraging lessons learned from prior pandemics. These measures include targeted vaccination, improved communication strategies to combat vaccine hesitancy, and the incorporation of social sciences to address barriers to public health interventions.
Avian influenza status in early 2025
Recent animal and human infections with highly pathogenic H5N1 avian influenza virus in the US have raised concerns related to an emerging pandemic. From 2024 through April 2025, there have been confirmed cases in 995+ dairy cow herds, 168+ million birds, 1650+ flocks, and at least 70 humans with the epizootic now present in all 50 states and human cases in 13 states and Canada. One mystery is the sporadic H5N1 infections that have occurred in humans with no known contact with infected animals, some of which resulted in severe disease; the first confirmed death in the US is an individual who likely contracted infection from wild birds that died on his property.1
While the H5N1 outbreak in dairy cows and associated farm workers has not resulted in sustained human-to-human transmission, the possibility of virus adaptation and widespread infections requires proactive and vigilant measures. Particularly given the continued presence of H5N1 in avian species. The recent CDC bird flu report highlights increased evidence of transmission to people underscoring the necessity of stronger surveillance approaches.2
The Global Virus Network (GVN) is an international coalition of virologists helping the international community improve the prevention, detection, and management of viral diseases. We recognize the threat that the H5N1 subtype of influenza A virus poses once efficient human-to-human transmission starts.
Here, we outline the status, information for the public and federal partners, risks, and mitigation opportunities to address the ongoing US epizootic, however, the information and recommendations are applicable globally.Is the virus mutating?Current sequence data from circulating highly pathogenic H5N1 avian influenza viruses indicate ongoing mutations and reassortment/mixing of genomic segments.3,4 The massive viral circulation has led to infection of an increasing range of mammals including suspected mammal-to-mammal transmission for minks, sea lions, and cows.5 In mammals, these viruses may acquire mutations that increase their ability to transmit and replicate efficiently in mammals, eventually including humans; however, this has yet to be demonstrated.3,6 Co-circulation of H5N1 viruses with swine or human seasonal influenza viruses, especially during the Northern hemisphere winter season, could lead to reassortant viruses that can efficiently spread in humans. The Pandemic Emergence Score is given by the CDC Influenza Risk Assessment Tool to estimate the risk of a pandemic. The CDC currently considers the virus to have a moderate future pandemic risk when compared to other Influenza A viruses.What is the situation now? How worried should the public be?
Until recently, human H5N1 infections globally were primarily the result of bird-to-human transmission, typically arising from direct or indirect contact with infected poultry or contaminated environments. These sporadic human infections increase the opportunities for a virus with sustained ability of human-to-human transmission. To understand risk, it’s vital that affected industry workers are kept appraised of health department and CDC advice. The proportion of undiagnosed human infections is unknown at present, and serosurveillance and respiratory surveillance of the population at greatest risk of exposure can enhance our understanding of risk to human health and to detect spillovers quickly. This requires heightened communication efforts to ensure the public is well informed. Measures like personal protective equipment (PPE) for those at risk and biosecurity in poultry farms generally are effective in preventing spread.7,8
The link and a snippet from the GVN press release follows:
Global Virus Network Issues Urgent Call to Action to Mitigate the Rising Threat of H5N1 Avian Influenza
By GVN | April 28, 2025 |
Top global virologists publish a comprehensive analysis and advocate for a multi-government initiative in the Lancet Regional Health—Americas
Tampa, FL, USA, April 28, 2025: Today, the Global Virus Network (GVN), representing eminent human and animal virologists from 80+ Centers of Excellence and Affiliates in 40+ countries, published a comprehensive analysis and call-to-action in The Lancet Regional Health—Americas on the North American avian influenza virus, or H5N1, outbreak. The GVN calls on world governments to address the threat of H5N1 avian influenza by enhancing surveillance, implementing biosecurity measures, and preparing for potential human-to-human transmission.
"Understanding the current landscape of H5N1 infections is critical for effective prevention and response," said Sten H. Vermund, MD, PhD, chief medical officer of the GVN and dean of the USF Health College of Public Health at the University of South Florida, USA. "The virus’ ability to infect both animals and humans, combined with recent genetic changes, underscores the importance of proactive surveillance and rapid response measures."
While I agree with the sentiments of this viewpoint, the $64 question is; is anybody listening?
A week ago, we looked at Two Surveys (UK & U.S.) Illustrating The Public's Lack of Concern Over Avian Flu, and on social media conspiracy theories abound about a `manufactured' pandemic.
Vaccine uptake is down for both COVID and Influenza, (along with Measles and other easily preventable diseases), while we continue to see new records set in the number of pediatric flu deaths each year.
Despite the known dangers of COVID reinfection (see CIDRAP COVID-19 reinfection ups risk of long COVID, new data show), post-pandemic mask wearing is almost non-existent outside of Asia (see Preprint - Continuing to be Cautious: Japanese Contact Patterns during the COVID-19 Pandemic).
While our global `don't test, don't tell' strategy may be politically or economically expedient in the short run - and the public may be comforted by this lack of information - we risk sleepwalking our way into the next pandemic
Just like we did (see The Most Predicted Global Crisis of the 21st Century) with COVID in 2019.
