FDA Panel Recommends Moderna mRNA Flu Vaccine for Older Adults

A Food and Drug Administration advisory panel unanimously recommended on Thursday the approval of Moderna's mRNA-based flu vaccine, mFlusiva, for older adults, marking a potential first for messenger RNA influenza shots. The FDA will consider the recommendation in making a final decision by early August.

The FDA's Vaccines and Related Biological Products Advisory Committee voted that the benefits of the vaccine appear to outweigh the risks for two age groups: adults 50 to 64, for which Moderna is seeking full approval, and adults 65 and older, for which it is seeking authorization while conducting additional testing. If the vaccine is cleared, Moderna is required to run a follow-up study of 400,000 people aged 65 and older.

In a late-stage trial of approximately 40,000 people aged 50 and older, the mRNA vaccine reduced flu cases by about 27% compared with a standard flu shot. A smaller study in people 65 and older showed the vaccine generated a strong protective immune response compared to a high-dose flu vaccine already recommended for that age group. Moderna stated its mRNA shot requires only two to three months from strain selection to vaccine rollout, down from about six months required for traditional flu shots.

The path to approval has been contentious. Earlier this year, the FDA initially issued a Refusal-to-File letter to Moderna for its application, stating the control arm did not reflect the "best-available standard of care." The agency's stated rationale was that the comparator should have been one of the preferred "enhanced" flu vaccines for adults 65 and older, such as a high-dose or adjuvanted product, rather than the standard-dose vaccine Moderna used in its main trial. Moderna challenged that decision, noting the FDA had previously agreed with the trial design in April 2024 and that it had provided separate data from a study comparing its vaccine to a high-dose shot. The FDA accepted the application a week after the initial refusal.

The review comes amid broader federal scrutiny of mRNA technology. The Department of Health and Human Services has been critical of mRNA vaccines under Health Secretary Robert F. Kennedy Jr. Earlier this year, the FDA's vaccine chief, who had personally handled the Refusal-to-File letter, departed the agency. The FDA currently has neither a permanent vaccine chief nor a commissioner.

Supporters emphasize that mRNA vaccines could offer a more flexible tool against influenza. Because the flu virus mutates and vaccine makers must choose strains months in advance, there can be a mismatch between the vaccine and circulating viruses. The faster development timeline for mRNA vaccines could allow for updates later in the year to better match circulating strains. An FDA advisory panel member stated that this technology "puts us in a better position to be prepared for emerging strains in the future."

Despite the panel's endorsement, questions remain about availability for the coming flu season. The shot must still receive final FDA approval and a formal recommendation from the Centers for Disease Control and Prevention's advisory committee, which has been blocked from convening by a federal judge. In August, the HHS canceled $500 million in funding for mRNA vaccine research and terminated a separate $590 million contract with Moderna for an avian flu vaccine. Moderna has indicated it will no longer invest in new Phase 3 vaccine trials for infectious diseases due to lack of U.S. market access.