Is This Bird Flu Strain the Next Pandemic Risk?

"A bird flu virus that has often been ignored because it mostly causes minor disease in birds has the potential to cause a human pandemic, says a team that has tracked how the H9N2 virus has become better adapted to infect people. The researchers say more surveillance of the virus is needed. In the past few years, surveillance has been focused on the avian influenza virus H5N1, which has spread across most continents and can cause severe disease and death in people."

"Since 2020, H5N1 has killed about 21 people. In North America, the virus is also spreading among dairy cows. Less attention is being paid to H9N2, says Kelvin To, a clinical microbiologist at the University of Hong Kong, despite the virus being the second most common strain of bird flu that infects people. H9N2 has caused 173 infections in people since 1998, mostly in China, says To, who presented his team's research at the Pandemic Research Alliance International Symposium in Melbourne, Australia, on 27 October."

H9N2 is a bird flu virus that primarily causes minor disease in birds but has acquired adaptations increasing its ability to infect humans. Surveillance efforts have focused on H5N1, which has spread across continents, killed about 21 people since 2020, and is spreading in North American dairy cows. H9N2 has caused 173 human infections since 1998, mostly in China, and many infections are likely missed because they are mild or testing targets H5N1. Genetic changes beginning around 2015 have increased H9N2 infectivity, and a 2024 isolate infected more human cells in laboratory experiments. No evidence of sustained person-to-person transmission currently exists. Expanded surveillance of H9N2 is needed.

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