FDA Approves Moderna's First mRNA Flu Vaccine for Seniors

The approval covers adults aged 50 to 64 under traditional approval and those 65 and older under accelerated approval, the latter contingent on Moderna completing confirmatory studies. The decision follows a late-stage trial of more than 40,000 participants, where mFlusiva reduced influenza cases by 26.6% compared with a standard-dose seasonal vaccine and elicited stronger immune responses than Sanofi's high-dose shot in older adults.

The FDA's review was lengthy. Earlier this year, the agency declined to proceed with Moderna's application over questions about how the vaccine compared with high-dose flu shots used in seniors. After additional discussions and a unanimous recommendation from an independent advisory committee in June, the agency cleared the vaccine.

Common side effects included temporary injection-site pain, fatigue, and fever, similar to other mRNA vaccines, with no major new safety concerns identified in trials. The vaccine's mRNA platform allows faster updates to match circulating strains, a potential advantage over egg-based production if flu viruses shift mid-season.

Moderna does not expect significant revenue from mFlusiva until late 2027, as it missed key purchasing cycles for the upcoming flu season. The approval also bolsters the company's pipeline, including a combination flu-COVID vaccine in development.

Federal health authorities say seasonal flu causes millions of illnesses, hundreds of thousands of hospitalizations, and thousands of deaths annually in the U.S., and they continue to recommend annual vaccination, especially for older adults and high-risk groups.