FDA Approves Moderna's mRNA Flu Vaccine mFLUSIVA
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- FDA approved Moderna's mFLUSIVA on Wednesday for older adults, making it the first licensed flu shot using messenger RNA technology and Moderna's fourth product on the U.S. market.
- Moderna received standard approval for adults 50-64 and accelerated approval for those 65+, agreeing to a Phase 4 post-licensure trial comparing mFLUSIVA against high-dose or adjuvanted vaccines preferentially recommended for that older age group.
- Phase 3 data presented to VRBPAC showed that adults 50-64 who received mFLUSIVA were 27% less likely to contract test-confirmed influenza than those who got the standard-dose comparator, though substantially more side effects — mostly mild and lasting one to two days — were reported in the mRNA arm.
- Vinay Prasad, then the FDA's head of biologics, issued a rare "refusal-to-file" notice in February over Moderna's choice of comparator; the decision was reversed within a week after Moderna disclosed it, and Prasad left the FDA at the end of April.
- VRBPAC, the FDA's vaccine advisory panel, voted unanimously in June that mFLUSIVA's benefits outweigh its risks.
- Moderna said doses will be available in advance of the coming flu season, with mRNA's faster manufacturing potentially allowing vaccine strains to be updated closer to the season and speeding a future pandemic flu licensure pathway; submissions are also under review in the EU, Canada, and Australia.
Why it matters: Moderna becomes the first mRNA flu shot on the U.S. market, entering a crowded space where adults 65+ currently get preferentially recommended high-dose or adjuvanted vaccines. The required Phase 4 trial in that older cohort will determine whether mFLUSIVA can claim meaningful superiority over incumbents.
