Why It Matters
The approval marks the first messenger RNA flu vaccine available in the United States, offering a new option for millions of older adults as health officials seek to reduce seasonal influenza hospitalizations and deaths. The authorization opens a pathway for rapid vaccine updates and potential combination shots protecting against multiple respiratory viruses.
What Happened
The Food and Drug Administration approved Moderna’s mRNA flu vaccine on Thursday for adults ages 50 to 64 under standard approval, and for adults 65 and older under accelerated approval. The accelerated pathway allows the vaccine to be used while Moderna continues a supplemental effectiveness study in senior populations.
The vaccine relies on the same mRNA technology deployed in COVID-19 vaccines. Moderna’s clinical trial enrolled approximately 40,000 participants and demonstrated a 27 percent reduction in flu cases compared to conventional flu shots. The company reported more frequent short-term side effects—arm pain, fatigue, headache, and fever—though adverse events were described as generally mild and temporary, with no major safety concerns identified.
The regulatory path was not straightforward. The FDA initially declined to review the application, citing concerns about the clinical trial design. Moderna contested that decision, and the agency agreed to proceed. An independent FDA advisory committee voted in June that the vaccine’s benefits outweighed its risks.
Dr. Marc Siegel, a medical expert, noted to Fox News that the vaccine “is geared for rapid turnaround once the yearly strains have been identified,” and stated it was found to be “25% to 30% more effective than the current flu vaccine.”
By the Numbers
27% — reduction in flu cases compared to standard flu vaccine in the clinical trial
40,000 — participants in the phase 3 clinical trial
50-64 — age range approved for standard FDA authorization
65+ — age range approved for accelerated authorization
57% — proportion of flu-related hospitalizations occurring in adults 65 and older during the 2024–2025 season
71% — proportion of flu-related deaths occurring in adults 65 and older during the 2024–2025 season
51 million — Americans infected with influenza during the 2024–2025 season
710,000 — flu-related hospitalizations during the 2024–2025 season
45,000 — flu-related deaths during the 2024–2025 season
Zoom Out
The mRNA platform has become a cornerstone of modern vaccine development since its deployment against COVID-19. A key advantage of messenger RNA technology is its ability to be reformulated quickly when pathogen variants emerge or seasonal strains shift, potentially reducing the lag between strain identification and vaccine availability that plagues traditional flu vaccines.
Moderna is pursuing a combined flu and COVID vaccine in a single seasonal injection, which could simplify immunization campaigns and improve compliance among older adults. The approval signals that regulators view mRNA flu protection as sufficiently safe and effective to authorize use, potentially opening doors for similar candidates from other manufacturers and laying groundwork for multi-pathogen combination shots.
What’s Next
The vaccine is authorized for the 2026–2027 flu season. Moderna will continue its ongoing effectiveness study in seniors, with results informing whether accelerated approval converts to standard approval. The company’s combination flu-COVID vaccine remains under development, with the goal of eventual single-shot administration for both viruses.