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The US should step up efforts to combat its year-long bird H5N1 flu outbreak and control the pandemic risk to people, an international group of virologists has warned.
The high historical human mortality rate from H5N1 suggests “the terrible consequences of underreacting to current threats”, say human and animal virologists from the Global Virus Network spanning more than 40 countries.
Their intervention on Tuesday highlights alarm at the proliferation of the H5N1 avian pathogen now detected in poultry in all 50 US states, infecting scores of people and causing at least one confirmed death.
They also raise concerns about the impact of turmoil in US scientific institutions on H5N1 surveillance efforts, as the Trump administration pushes through spending cuts and curbs communications.
In an article in the journal The Lancet Regional Health-Americas, the scientists call on governments around the world to enhance surveillance, implement biosecurity measures and prepare for potential people-to-people spread.
“Currently, the risk for humans not handling infected animals is low, because the viruses are not able to transmit between people,” said Prof Marion Koopmans, co-author of the Lancet paper and head of the viroscience department at the Netherlands’ Erasmus Medical Centre.
“But that can change abruptly if the virus picks up mutations, which can happen if it continues to circulate in mammals. Then we would be looking at a new possible pandemic scenario.”
The US outbreak has spread nationwide since March 2024, affecting more than 1,000 dairy herds and killing or triggering the culling of tens of millions of poultry.
At least 70 human cases have been identified, with one person dying in Louisiana, according to the Centers for Disease Control and Prevention.
Both the previous US administration of Joe Biden and the current government of President Donald Trump have drawn criticism for failing to do more to stop the spread.
The longer the outbreak persists and the wider it spreads, the greater the risk H5N1 pathogens will mix genetic material with other viruses and become more transmissible between species. Last month, the UK reported the first known H5N1 case in a sheep.
The Global Virus Network scientists call for the fast sharing of US genomic sequencing information and associated metadata, such as when and where samples were taken.
Current US genomic data suggests “ongoing mutations” of highly pathogenic H5N1 viruses and suspected cases in mammals such as sea lions and mink, the scientists say.
If the pathogens exchange genetic material with swine or human seasonal influenza viruses, this could make them transmissible between humans, they add.
The Trump administration has also curbed communications by various scientific bodies, as it seeks to suppress research in areas including diversity, vaccines and climate change.
“We deplore restrictions placed on CDC and other public health communications consequent to the current US political climate,” the virologists say. “This hampers the effectiveness of full implementation of protective public health measures.”
Existing bird flu testing is insufficient to stop its spread, which has “held egg prices in the US at an all-time high” because of its impact on poultry flocks, the scientists say.
Government-mandated milk testing is a “critical first step” on surveillance but “not widespread enough” because implementation varies by state, they add.
