NBC News The current U.S. stockpile of H5N1 flu shots likely won’t offer much protection in the event of a pandemic, vaccine researchers said.
Wild birds and poultry flocks alike continue to drop dead from the highly pathogenic bird flu that began spreading globally in 2020. Almost 59 million commercial birds have already been culled in the United States.
It’s the broadest outbreak of this type of avian flu, known as H5N1, since it was first identified in China in 1996.
The virus’s proliferation and high fatality rate have prompted questions about two types of possible vaccines: those for birds and those for humans. H5N1 kills almost all the birds it infects; among reported cases in people since 2003, the death rate has been 56%.
The U.S. Agriculture Department announced in April that it had started testing several vaccine candidates for poultry.
Vaccines for people, meanwhile, would only be considered if the virus eventually undergoes a complicated string of mutations that allow it to spread from person to person. There’s no evidence of that yet. The U.S. recorded its only human case of H5N1 last April — the person was involved in culling poultry with presumed infections in Colorado. The United Kingdom reported two cases Tuesday, both poultry workers with asymptomatic infections detected via routine testing. Chile reported one infection in March and Ecuador one case in January.
But scientists have long considered H5N1 to have pandemic potential. The U.S. has a stockpile of H5N1 flu shots in case such a crisis arises, but three experts said it would likely prove insufficient should this particular type of avian flu start infecting people. The shots have only been administered in trials and were derived from strains that circulated in 2004 and 2005.