Moderna Says FDA has Nixed its Application for New mRNA Flu Vaccine

The US Food and Drug Administration (FDA) is refusing to consider Moderna’s application for a new flu vaccine made with Nobel Prize-winning mRNA technology, the company announced, Lauran Neergaard and Matthew Perrone reported for the Associated Press (AP).

Moderna received what’s called a “refusal-to-file” letter from the FDA that objected to how it conducted a 40,000-person clinical trial comparing its new vaccine to one of the standard flu shots used today. (Photo: Airman 1st Class Anna Nolte, U.S. Air Force)

The news is the latest sign of the FDA’s heightened scrutiny of vaccines under Health Secretary Robert F. Kennedy Jr., particularly those using mRNA technology, which he has criticized before and after becoming the nation’s top health official.

Moderna received what’s called a “refusal-to-file” letter from the FDA that objected to how it conducted a 40,000-person clinical trial comparing its new vaccine to one of the standard flu shots used today.

That trial concluded the new vaccine was somewhat more effective in adults 50 and older than the standard shot.

The letter from FDA vaccine director Dr. Vinay Prasad said the agency doesn’t consider the application to contain an “adequate and well-controlled trial” because it didn’t compare the new shot to “the best available standard of care in the US at the time of the study.”

Prasad’s letter pointed to some advice FDA officials gave Moderna in 2024, under the Biden administration, which Moderna didn’t follow.

Moderna said that feedback indicated it was acceptable to use the standard-dose flu shot the company had chosen, but that another brand specifically recommended for seniors would be preferred for anyone 65 and older in the study.

Still, Moderna said, the FDA did agree to let the study proceed as originally planned.