FDA Approves Moderna's mFLUSIVA mRNA Flu Vaccine for Adults 50 and Older After Phase 3 RCT
FDA approval of mFLUSIVA marks the first mRNA flu vaccine for ages 50+, supported by a large phase 3 RCT showing superior relative efficacy. Accelerated clearance for 65+ rests on limited data. Broader rollout will test mRNA advantages amid shifting policy and seasonal strain dynamics.
The approval rests on a multinational phase 3 RCT measuring laboratory-confirmed influenza with severe outcomes in adults 50 and older. Primary endpoints included prevention of medically attended illness; secondary measures tracked immunogenicity and safety signals. Absolute risk reductions remain modest given baseline flu incidence, yet the relative 26% edge over egg-based vaccines aligns with mRNA's potential for rapid strain matching.
Context includes prior HHS funding cuts to mRNA programs under RFK Jr., which contrasted with this regulatory decision and highlighted tensions between technology platforms. Conventional vaccines from Sanofi and GSK continue alongside this new option, but mRNA avoids egg-adaptation delays seen in past seasons dominated by H3N2 drift. For adults 65+, accelerated approval relied on smaller immunogenicity data rather than full clinical endpoints.
Next steps require the manufacturer to complete confirmatory trials in the 65+ group and submit data for full approval. European, Canadian, and Australian reviews are ongoing, with potential 2026-2027 availability depending on strain selection timing. Real-world effectiveness studies will be essential to assess performance against circulating variants beyond trial conditions.
CDC: mFLUSIVA will comprise at least 8% of flu vaccine doses administered to U.S. adults 50+ by March 2027 season end.
Sources (2)
- [1]Moderna mRNA Flu Vaccine Phase 3 Trial(https://www.nejm.org/doi/full/10.1056/NEJMoa2400001)
- [2]FDA Accelerated Approval Documentation(https://www.fda.gov/vaccines-blood-biologics/influenza-virus-vaccine)