The US Food and Drug Administration has approved Moderna's mFlusiva for adults aged 50 and older, making it the first seasonal influenza vaccine based on messenger RNA technology to reach the American market. The decision gives full traditional approval for people aged 50 to 64 and accelerated approval for those 65 and older, according to the company and the Associated Press.
Moderna said limited supplies could reach selected retailers for the 2026-2027 respiratory-virus season. The new option arrives as pharmacies begin receiving other annual flu shots and as older adults remain especially vulnerable to hospitalization and death from influenza. FDA briefing materials estimate that the disease has caused between 6,300 and 52,000 US deaths annually since 2010.
Traditional approval for the younger group rests chiefly on a randomized, observer-blinded Phase 3 study involving about 40,000 adults. FDA reviewers reported relative vaccine efficacy of 26.6 percent against laboratory-confirmed influenza-like illness compared with a standard-dose flu vaccine, meaning the mRNA group recorded roughly 27 percent fewer confirmed cases than the comparison group.
For adults aged 65 and above, regulators used the accelerated pathway after a smaller Phase 3 study found that mFlusiva generated immune responses that met noninferiority and superiority criteria against a high-dose vaccine recommended for seniors. Moderna must conduct a Phase 4 confirmatory study to verify clinical benefit in that age group while post-market safety monitoring continues.
FDA documents said reported reactions were more frequent with mFlusiva than with comparator shots but were mainly mild or moderate. AP listed temporary injection-site pain, fever, headache, fatigue and body aches, while reporting that the clinical data showed no major safety problem. Regulators also identified evidence gaps involving frail adults, some high-risk groups, duration of protection and coadministration with other vaccines.
The approval follows an unusual review in which the FDA initially declined to consider Moderna's application over the choice of comparator for seniors, then reversed course after the company challenged that decision. An independent FDA advisory panel voted 9-0 in June that benefits outweighed risks in each age group. Because mRNA vaccines can be redesigned and produced faster than many egg-based shots, specialists see the platform as another option when circulating flu strains change, although annual strain matching and further evidence will remain important.
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