FDA Approves Moderna’s mRNA Flu Vaccine mFlusiva

Moderna has secured US Food and Drug Administration (FDA) approval for mFlusiva, its mRNA influenza vaccine, making it the first mRNA-based vaccine authorised in the US for the prevention of seasonal flu. Announced on 6 August 2026, the approval covers all adults aged 50 years and older, with traditional approval for the 50-to-64 age group and accelerated approval for those aged 65 and older.

The 50-to-64 approval was supported by a Phase III trial that enrolled more than 40,000 participants, with mFlusiva showing superiority over standard-dose licensed vaccines. A separate Phase III trial compared mFlusiva against a high-dose comparator in the 65-and-older group, with Moderna required to conduct a postmarketing trial as part of the accelerated approval. The approval caps a difficult regulatory journey that included a rare Refuse to File letter in February 2026 over the comparator design, an amended application accepted within a week, and a unanimous June 2026 VRBPAC vote in favour.

mFlusiva is Moderna’s fourth FDA-approved vaccine. William Blair analysts have set a conservative peak sales forecast of $1.16 billion, noting that mRNA vaccines can be updated for new strains more quickly than traditional protein-based vaccines. However, the vaccine still requires a CDC Advisory Committee on Immunization Practices (ACIP) recommendation to be included in national immunisation programmes, with the next meeting scheduled for mid-October 2026. The vaccine also faces uncertain adoption dynamics amid US regulatory turbulence around mRNA technology, including the cancellation of $500 million of federal mRNA contracts in August 2025.

The commercial signal is a validation win for mRNA vaccine technology at exactly the moment US mRNA policy risk is at its most acute. mFlusiva’s commercial trajectory now hinges on the mid-October ACIP recommendation. Expect GSK, Sanofi and CSL Seqirus to sharpen their positioning across the seasonal flu vaccine competitive set as mRNA challengers move toward market entry.

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