FDA staff say Moderna flu shot may protect older adults better

For Americans over 65, the question is simple: does this bring the country closer to a better flu shot for the people most likely to be hospitalized or die from influenza? FDA staff said Moderna’s experimental seasonal vaccine, MFLUSIVA, has cleared an important scientific hurdle by producing an immune response that may support effectiveness in adults 65 and older, while also showing superior relative vaccine efficacy in adults 50 to 64 versus a standard-dose flu shot.

The agency’s staff briefing, however, stopped short of declaring victory. Reviewers said the older-adult evidence rests mainly on immunogenicity, not a direct comparison with the high-dose and adjuvanted vaccines the Centers for Disease Control and Prevention and its Advisory Committee on Immunization Practices already prefer for people 65 and older. Staff also pointed to limited one-season data, more short-term side effects, and the need for postmarket studies in seniors.

That leaves the key scientific and regulatory question for the U.S. Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee, which is scheduled to meet June 18 from 8:30 a.m. to 4:00 p.m. Eastern Time. Members will discuss and vote on MFLUSIVA, the mRNA influenza vaccine Moderna wants approved for people 50 years of age and older, with traditional approval sought for adults 50 to 64 and accelerated approval sought for adults 65 and older.

If the FDA ultimately signs off, the shot would become the first mRNA-based seasonal flu vaccine sold in the United States. Moderna’s pivotal phase 3 trial enrolled 6,102 participants, and the company has said the vaccine posted an overall relative efficacy of 26.6% versus standard-dose comparators, with a 27.4% point estimate in adults 65 and older. Those results were published in The New England Journal of Medicine in May, putting the data squarely in front of regulators and investors ahead of the vote.

The FDA had rejected Moderna’s flu vaccine application in February before later accepting an amended version after the company agreed to run a post-approval study in adults 65 and older. The shifting review helped send Moderna shares up about 2% in morning trading after the briefing documents became public, and Jefferies analyst Andrew Tsai projected $750 million in U.S. flu and COVID-flu combo vaccine sales by 2030 if the product is approved.

The immediate public-health value of mRNA here is still not settled. FDA staff say the data may be enough to support effectiveness, especially in older adults, but the missing head-to-head comparison with better-established senior vaccines means the promise is real without yet being proven superior. For a country where older adults carry much of the flu burden, that distinction matters.