FDA Approves mFLUSIVA, the First mRNA-Based Seasonal Flu Vaccine

The FDA approved Moderna's mFLUSIVA (mRNA-1010) on Aug 5 for adults 50 and older — the first mRNA-based seasonal influenza vaccine ever licensed in the US. Regulators granted traditional approval for ages 50–64 and accelerated approval for ages 65+, conditioned on a postmarketing confirmatory study in the older cohort. The decision rests on a Phase 3 trial of 40,805 adults across 11 countries (NCT06602024) showing 26.6% relative efficacy against influenza-like illness versus a standard-dose comparator (27.4% in adults 65+), rising to 47.9% against severe outcomes. The approval caps a dramatic regulatory turnaround: a then-top FDA official issued a rare refusal-to-file in February 2026 amid heightened vaccine scrutiny under HHS Secretary Robert F. Kennedy Jr., which the agency reversed within days after Moderna publicly challenged the decision; VRBPAC then voted unanimously 9-0 (twice) on Jun 18 that benefits outweigh risks. mFLUSIVA becomes Moderna's fifth globally approved product and fourth FDA approval, with supply expected at select US retailers ahead of the 2026–27 flu season. mRNA-1010 is also under regulatory review in the EU, Canada, and Australia.