The FDA has approved the nation's first flu vaccine made with mRNA technology, the manufacturer, Moderna, announced on Thursday.
The vaccine, which is based on the same messenger RNA platform used in COVID-19 shots, has been fully approved for adults ages 50-64 ahead of the 2026-2027 flu season.
For adults 65 and older, the vaccine received accelerated approval, which allows the vaccine to be used while Moderna completes an additional study to confirm its effectiveness in seniors.
Experts say mRNA vaccines can be updated more quickly to protect against changes in circulating flu strains.
The approval was based on a phase 3 clinical trial including around 40,000 participants, in which the new vaccine was found to effect a 27% reduction in flu cases compared to a standard flu vaccine.
No major safety concerns were identified in the trial, according to the announcement.
It was found to have more short-term side effects than conventional flu shots – including arm pain, fatigue, headache and fever – although these were noted to be generally mild and temporary.
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"This is not a universal vaccine, but is geared for rapid turnaround once the yearly strains have been identified," said Dr. Marc Siegel, Fox News senior medical analyst.
"It’s similar to the COVID vaccine and was found to be 25% to 30% more effective than the current flu vaccine," he added. "It’s geared to protect the elderly."
Older adults face the biggest risk of severe influenza. During the 2024-2025 season, people 65 and older accounted for 57% of flu-related hospitalizations and 71% of deaths, according to the Centers for Disease Control and Prevention.
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An estimated 51 million Americans contracted the flu during the 2024-2025 season, with the virus linked to around 710,000 hospitalizations and 45,000 deaths, per the above source.
Earlier this year, the new mRNA vaccine faced a regulatory setback when the FDA initially refused to review Moderna's application, citing concerns about the design of its clinical trial, the Associated Press reported.
Moderna disputed the decision, and the FDA later agreed to move forward with the review.
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In June, an independent FDA advisory committee agreed that the vaccine's benefits outweighed its risks, paving the way for its approval.
Looking ahead, the approval could pave the way for combination vaccines that protect against multiple respiratory viruses at once, according to Moderna.
The company said it is pursuing a combined flu/COVID vaccine, with the goal of giving people one seasonal shot.
