FDA approves first mRNA-based flu vaccine
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- Reviewed by Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
The 2026–2027 influenza season is fast approaching, but now there’s a new weapon in the vaccine arsenal. On August 5, 2026, the FDA approved mFLUSIVA, the first mRNA influenza vaccine for people ages 50 to 64. The agency also issued an accelerated approval for use in adults ages 65 and older, which allows the vaccine to be used widely in advance of full approval.
Manufactured by Moderna, mFLUSIVA uses the same technology that produced the COVID-19 vaccines. Unlike traditional flu vaccines, which use an inactivated virus grown in eggs or cells, mRNA vaccines use a small bit of genetic code, which instructs the body to produce a harmless virus protein that triggers the body’s immune response to that virus.
Manufacturing speed sets mRNA vaccines apart. They can be updated and produced much faster than standard vaccines — a critical advantage, since flu strains can evolve rapidly and become less like the strains a vaccine was developed to target.
The mRNA vaccine may also offer slightly more protection compared with traditional flu vaccines, according to a clinical trial involving participants ages 50 to 64. Among just over 20,000 people who were given mFLUSIVA, 411 caught the flu within six months, compared with 557 from a group of similar size who’d received the standard flu shot.
However, the trial didn’t compare the mRNA vaccine with the stronger flu vaccines often recommended for people over 65, “so we don’t yet know whether it works better than those options,” says Kizzmekia S. Corbett-Helaire, assistant professor of immunology and infectious diseases at the Harvard T.H. Chan School of Public Health.
Side effects were about twice as common in the mRNA vaccine–treated group, including injection site pain, fatigue, headache, and muscle aches — though most reactions were temporary and mild to moderate. Serious adverse events were rare in both groups.
The vaccines should be available in time for flu season. But “don’t put off getting vaccinated while waiting for a particular shot,” says Corbett-Helaire, as traditional vaccines remain a safe and reliable way to reduce your flu risk. It’s not yet known if the vaccines will be covered by insurance, so check before scheduling a jab.
Image: © FatCamera/Getty Images
About the Author
Joyce Hendley, Staff Writer
About the Reviewer
Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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