FDA Approves Moderna's mRNA Flu Shot for Adults 50 and Up

The Food and Drug Administration has approved a seasonal flu vaccine from Moderna built on mRNA technology, the drugmaker announced Wednesday. It is the first influenza vaccine using the technology to receive FDA approval.

The vaccine, called mFLUSIVA, is approved for adults ages 50 and older. Moderna said it expects the shot to be available for the 2026-27 flu season.

The approval "reflects the ongoing potential of our mRNA platform to help address important public health challenges through continued scientific innovation," the company said in a statement. "We are grateful to the clinical trial participants, investigators, regulators and Moderna teams whose contributions made this milestone possible."

The decision follows an unusual regulatory detour. The FDA had said it would refuse to consider Moderna's application, then reversed course about a week later, saying discussions with the company "led to a revised regulatory approach and an amended application, which FDA accepted."

The dispute centered on a 40,000-person clinical trial that found the new vaccine was more effective in adults 50 and older than one of the standard flu shots in use today. In a refusal-to-file letter, FDA vaccine director Dr. Vinay Prasad faulted the trial for not including another brand specifically recommended for people 65 and older.

Moderna then revised its application, seeking full approval for adults 50 to 64 and accelerated approval for those 65 and older. The company also agreed to conduct an additional study of the vaccine's use in older adults.

The FDA is part of the Department of Health and Human Services, whose secretary, Robert F. Kennedy Jr., has repeatedly criticized mRNA technology.

CBS News medical correspondent Dr. Céline Gounder, editor-at-large for public health at KFF Health News, said on "CBS Mornings" on Thursday that most flu vaccines are still grown in chicken eggs, a slower process, while mRNA vaccines can be made faster and updated more efficiently.

"If we had a flu pandemic hit tomorrow, if you use the egg-based technology, it would take 18 months to produce enough flu vaccine for that pandemic strain to cover a quarter of the world's population," she said. "With an mRNA vaccine, you could do it much more quickly."

Side effects include pain at the injection site, fatigue and headache, Gounder said, adding that trial results showed effectiveness higher than standard flu vaccines.