The Food and Drug Administration has granted full approval to Moderna’s mRNA flu vaccine, marking the first time this technology has been used for seasonal influenza protection. The agency approved the shot, known as mFLUSIVA, for adults ages 50 and older, while granting accelerated approval for those 65 and up. This decision comes as public health officials track a challenging respiratory season, with the CDC estimating 45,000 flu-related deaths last year, though vaccination prevented about 12,000 of them.
Rapid Production Timeline
Manufacturing a flu vaccine involves a long process that can take up to six months, creating a window where circulating viruses might evolve before the shot reaches the public. Traditional egg-based vaccines require this extended timeline to grow the virus in fertilized eggs, which limits the ability to adjust the formulation quickly. Moderna’s mRNA approach uses technology similar to its COVID-19 vaccine, which the company says allows for faster redesign and production. This speed could help match the vaccine to rapidly changing influenza strains, a persistent problem for seasonal shots.
The FDA approved mFLUSIVA based on a phase 3 trial involving more than 40,000 adults in 11 countries. Researchers found the mRNA vaccine was superior to standard-dose shots in preventing flu-like illness confirmed by lab tests. For adults ages 50 to 64, the trial showed approximately 27% greater relative efficacy compared to the traditional option. The company expects the vaccine to be available in the United States for the 2026 to 2027 respiratory virus season.
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Expert Perspectives
Doctors emphasize that while this is a scientific milestone, the mRNA flu shot should not immediately replace every other vaccine. Dung Trinh, an internist with MemorialCare Medical Group, noted that adults over 50 face a progressively higher risk of complications from influenza. He described the approval as an important addition to the prevention toolkit, highlighting that mRNA technology has now proven effective beyond the COVID-19 pandemic.
David Cutler, a family medicine physician at Providence Saint John’s Health Center, offered a cautiously favorable view. He pointed out that the approval for those 65 and older is “accelerated,” requiring additional post-approval evidence to confirm clinical effectiveness, such as preventing hospitalization or death. Cutler suggested waiting for another season of real-world data before declaring the mRNA option superior to established high-dose vaccines.
Side effects reported in trials included headache, fatigue, joint pain, and muscle soreness at the injection site. As with any medical intervention, a healthcare professional can advise on the safety profile and whether the new option is appropriate for an individual’s specific health needs.