The U.S. Food and Drug Administration (FDA) on Wednesday approved Moderna’s mRNA-based seasonal flu vaccine, mFLUSIVA, for adults 50 and older, marking the first mRNA flu shot authorized in the U.S.
The vaccine will be available for the 2026-2027 flu season, pending additional data submission for adults 65 and older, Moderna announced. In a late-stage clinical trial, mFLUSIVA demonstrated 27% greater efficacy than standard flu vaccines in adults aged 50 to 64. Side effects were mostly mild and short-lived, though slightly more common than with traditional shots.
FDA’s conditional approval for seniors 65+ requires Moderna to submit further comparative data from the upcoming flu season to confirm its effectiveness against high-dose vaccines currently recommended for that age group.
How mFLUSIVA works
mFLUSIVA uses messenger RNA (mRNA) technology, the same platform as Moderna’s and Pfizer’s COVID-19 vaccines. Unlike traditional flu vaccines, which take about six months to manufacture after strain selection, mRNA vaccines can be produced in two to three months, allowing faster adaptation to circulating flu strains.
Dr. Ofer Levy, director of the Precision Vaccines Program at Boston Children’s Hospital, highlighted the advantage: “If you’re choosing the strain half a year before, how good can we be at sharpshooting?” Traditional flu vaccines typically range from 22% to 56% effectiveness, according to the Mayo Clinic.
Regulatory back-and-forth
The FDA initially refused to review Moderna’s application earlier this year but later reversed course. The agency required Moderna to conduct an additional clinical trial for adults 65+, a condition Moderna accepted. The vaccine’s approval follows a 40,000-person trial showing improved efficacy in adults 50 and older.
Public health impact
The flu hospitalizes hundreds of thousands of Americans annually, with tens of thousands of deaths, per the Infectious Diseases Society of America. Older adults and young children face the highest risks of severe illness.
Moderna CEO Stéphane Bancel stated: “Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America’s seniors.”
Next steps
Moderna plans to submit further data from the 2024-2025 flu season to solidify approval for adults 65+. The company did not specify a timeline for broader age group approvals beyond the current scope.