FDA Grants First mRNA Flu Vaccine Approval for Adults 50+

The U.S. Food and Drug Administration approved Moderna's mRNA flu vaccine, mFlusiva, for adults 50 and older, marking the first such product in the United States. The agency gave standard approval for ages 50-64 and accelerated approval for those 65 and older, requiring a post-marketing study to confirm clinical benefit in the older group.

The vaccine uses messenger RNA to instruct cells to produce a viral protein, prompting an immune response, a method similar to that used in COVID-19 shots. Experts noted that mRNA technology allows strain selection later in the year, potentially improving match with circulating viruses compared with traditional egg-based vaccines.

In clinical trials involving more than 40,000 participants, the mRNA vaccine showed about a 27% higher effectiveness than standard flu shots for the 2024-25 season. Side effects such as injection-site pain, muscle aches, fever and headache were generally mild to moderate and resolved within days; serious adverse events were rare and comparable to those seen with conventional vaccines.

"The Food and Drug Administration’s approval of a new mRNA flu vaccine is welcome news and provides another important option to help protect people from a virus that sends hundreds of thousands of Americans to the hospital each year and claims thousands of lives," said Dr. Ronald G. Nahass, president of the Infectious Diseases Society of America.

Regulatory advisers voted unanimously that the vaccine’s benefits outweigh its risks. However, the FDA noted that the trial’s control arm did not reflect the best-available standard of care for adults 65 and older, leading to the accelerated-approval pathway.

Health experts said the new shot offers a promising option for the 50-64 age group, while emphasizing the need for real-world effectiveness data in the 65-plus population before making stronger recommendations.

Moderna aims to distribute the vaccine this fall, but availability may be limited because pharmacies typically order flu vaccines earlier in the year. Insurance coverage remains uncertain until the CDC’s advisory committee reviews the product and issues guidance.