The US Food and Drug Administration on Thursday issued recommendations for the composition of influenza shots for the upcoming respiratory virus season, but without input from its independent vaccine advisers.
The FDA’s Vaccines and Related Biological Products Advisory Committee had been scheduled to meet Thursday to weigh in on the composition of the flu shots, but that session was canceled without explanation in late February.
Instead, experts from within the FDA, the US Centers for Disease Control and Prevention and the US Department of Defense gathered Thursday to go over surveillance data from the US and around the world about flu viruses that are currently circulating.
The FDA is recommending that flu vaccines for the 2025-26 season be trivalent, protecting against two strains of influenza A and one of influenza B.
“The FDA anticipates that there will be an adequate and diverse supply of approved trivalent seasonal influenza vaccines” for the upcoming virus season, it said in a statement.
There are several ways to make flu vaccines, but the most common is to grow the selected candidate viruses in chicken eggs, a painstaking operation that takes months to finish.
For that reason, selection of the strains that will be included in flu vaccines is carefully orchestrated to be sure manufacturers can deliver the shots to doctors’ offices and pharmacies in time.
In order for flu vaccines to be sold in the US, they must contain strains that are officially selected by the FDA.
That decision typically comes after a meeting of the World Health Organization’s Global Influenza Surveillance and Response System, a network of seven collaborating centers and four essential regulatory labs, which are based in the US, UK, Japan, China, Russia and Australia. Both the CDC and the FDA are members.
These experts meet twice a year — in the fall and spring — to choose strains for countries in the Southern and Northern Hemispheres. WHO’s own vaccine recommendations for 2025-26 generally parallel those of the FDA.
Typically, the 17-member FDA vaccine committee would meet next and publicly discuss the recommendation and make its own endorsement, and then the agency would make its final decision.
The cancellation of the committee meeting had prompted concerns about the timing of and access to flu shots for this fall. “I’m glad that they’ve come out with the influenza recommendation in a timely manner,” Dr. Paul Offit, a member of the independent advisory committee and director of the Vaccine Education Center at the Philadelphia Children’s Hospital, said Thursday.
The 2024-25 flu season – the worst in the US in more than a decade – is believed to have peaked in early February. The CDC estimated in early March that there had been at least 40 million illnesses, 520,000 hospitalizations and 22,000 deaths caused by flu this season.