FDA approves Moderna's first mRNA flu vaccine
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- FDA approved Moderna's mFlusiva for older adults — the first licensed flu shot using mRNA technology — with some doses expected to be available before the upcoming flu season.
- Moderna's Phase 3 trial showed adults 50-64 who received mFlusiva were 27% less likely to contract test-confirmed influenza than those given a standard-dose comparator, though substantially more side effects were reported in the mRNA arm.
- Vinay Prasad, then the FDA's head of biologics, issued a rare refusal-to-file notice in February saying the available data package was insufficient; his decision was reversed two weeks later and Prasad left the agency at the end of April.
- FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted unanimously in June that the vaccine's benefits outweighed its risks.
- mFlusiva received standard approval for adults 50-64 and accelerated approval for adults 65+, with Moderna required to run a Phase 4 post-licensure trial comparing it to the high-dose or adjuvanted vaccines preferentially recommended for that older age group.
- mRNA flu vaccines can be manufactured faster than egg-based or cell-based shots, potentially allowing strain selection closer to flu season and a faster licensure pathway for pandemic flu vaccines.
- mFlusiva has been accepted for regulatory review in the European Union, Canada, and Australia, with submissions to additional countries planned for later this year.
Why it matters: Moderna's mFlusiva enters a crowded U.S. flu vaccine market with a 27% efficacy edge over standard-dose comparators in adults 50-64, though mRNA recipients experienced substantially more (mostly mild, one-to-two-day) side effects. The accelerated approval for adults 65+ — the group that most needs protection — is contingent on a Phase 4 trial against the high-dose vaccines currently preferentially recommended for them.
