Health officials are preparing to make up-to-date bird flu vaccines available in the event of a pandemic.
The Food and Drug Administration (FDA) presented plans Thursday to its Vaccines and Related Biological Products Advisory Committee (VRBPAC).
“I think we are all … doing everything we can do to be as prepared as possible to shorten the time needed to get a vaccine to market,” said Jerry P. Weir, Ph.D., director of the FDA’s Division of Viral Products.
Eighteen human cases of highly pathogenic avian influenza A(H5) have been reported in the U.S. this year, mostly among people in contact with dairy cattle or poultry. Currently, the risk of bird flu is low for the general population.
Three H5 vaccines are licensed in the U.S., two of which are approved for children. However, they were approved in 2007, 2013 and 2020, and health officials said the strains are outdated. The H5 viruses in the U.S. are from clade 2.3.4.4b.
FDA leaders proposed having manufacturers test the safety and immunogenicity of updated vaccines and submit a strain change supplement to their license before a pandemic.
“With ongoing inter-pandemic updates to the prototype vaccine coupled with better and better tools to forecast effective pandemic vaccine composition, we may save critical pandemic response time having the updated vaccines when we need them without waiting for a strain change,” said David C. Kaslow, M.D., director of the FDA’s Office of Vaccines Research and Review.
VRBPAC member Melinda Wharton, M.D., M.P.H., applauded the proposed update to the process.
“Even if we’d never have to use a 2.3.4.4b vaccine, I think it would likely be a very good investment,” said Dr. Wharton, associate director for vaccine policy and clinical partnerships at the Centers for Disease Control and Prevention’s (CDC’s) National Center for Immunization and Respiratory Diseases (NCIRD). “And should we end up needing one of those vaccines in the future or something similar, I think we’d be in a much better situation by having these updated pre-pandemic vaccines in the inter-pandemic period.”
Highly pathogenic avian influenza H5 viruses entered the U.S. in late 2021 and have caused outbreaks in wild birds, commercial poultry, marine mammals and dairy cows.
While human cases have been sporadic, there’s no indication the virus has changed in a way that would make it easier to spread among humans, according to Todd Davis, Ph.D., M.S.P.H., acting branch chief in the Virology, Surveillances and Diagnosis Branch of NCIRD’s Influenza Division.
Still, health officials repeatedly said flu can be unpredictable, and they want to be prepared. Officials from the Biomedical Advanced Research and Development Authority (BARDA) have a stockpile with adjuvants, antigen and final containers of vaccine manufactured from candidate vaccine viruses. The CDC and World Health Organization have extensive flu surveillance, and the stockpile is updated as needed.
BARDA and vaccine manufacturers GSK and CSL Seqirus already are conducting trials on updated H5 vaccines in adults and expect to have data ready next year. Officials said vaccine trials will include children contingent on funding.
BARDA’s goal in the event of a pandemic is to deliver the first doses of pandemic vaccine within three months of a pandemic declaration, and to have sufficient supply to meet public demand within four months of a declaration and enough for the entire U.S. population within six months of a declaration.
Dr. Weir noted the country is in a much better position than during the 2009 flu pandemic as it now has a library of candidate vaccine viruses that vaccine manufacturers can use, including four from clade 2.3.4.4b developed by the CDC and FDA.
VRBPAC member Arnold S. Monto, M.D., encouraged consideration of innovative vaccines but also urged a process that moves quickly.
“One lethal case of H5N1 might change the process in terms of the alarm bells sounding,” said Dr. Monto, Thomas Francis Jr. Collegiate Professor Emeritus of Public Health at the University of Michigan. “We haven’t had a severe case, but the whole story of the unpredictability, the lack of ability to predict dairy cattle spread is a lesson to be prepared for the unexpected.”
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