The U.S. Food and Drug Administration has approved a new seasonal flu vaccine from Moderna that uses mRNA technology, the drugmaker announced Wednesday.

Called mFLUSIVA, it is approved for adults ages 50 and older. It’s the first influenza vaccine using mRNA technology to receive FDA approval.

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

The FDA is part of the U.S. Department of Health and Human Services, and the approval comes despite repeated criticism of mRNA technology by Health and Human Services Secretary Robert F. Kennedy Jr. Last year, Kennedy canceled 22 vaccine development projects that use mRNA technology.

CBS News medical correspondent Dr. Céline Gounder, who is also editor-at-large for public health at KFF Health News, explained on “CBS Mornings” Thursday that most flu vaccines are still grown in chicken eggs, which takes longer to produce. But mRNA vaccines can be produced much more quickly, which means “you can also update the vaccine more efficiently.”

“Just to give you some perspective, 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.”

The FDA earlier this year said it would refuse to consider Moderna’s application. But it reversed course about a week later and stated it would allow the vaccine to proceed to review after discussions with Moderna “led to a revised regulatory approach and an amended application, which FDA accepted.”

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

Moderna subsequently revised its application to seek full vaccine approval for adults aged 50 to 64 and accelerated approval for adults aged 65 and older. The drugmaker also agreed to conduct an additional study of the drug’s use by older adults.

As for side effects that people should be aware of, Gounder said they include pain in the injection site, fatigue and headache. She added that in the trials, Moderna saw the vaccine effectiveness to be higher than standard flu vaccines.

Moderna said it expects to have mFLUSIVA available for the 2026-27 flu season.