Moderna's New mRNA Flu Vaccine Rejected by FDA

Agency cites concerns over clinical trial design in 'refusal-to-file' letter to the company.

Published on Feb. 11, 2026

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The U.S. Food and Drug Administration has refused to consider Moderna's application for a new flu vaccine made with mRNA technology, the company announced. The FDA cited concerns about Moderna's use of a 40,000-person clinical trial that showed improved effectiveness in adults 50 and older compared to a standard flu shot.

Why it matters

This decision is the latest sign of heightened FDA scrutiny of vaccines, particularly those using mRNA technology, under the leadership of Health Secretary Robert F. Kennedy Jr. The move could impact the development and availability of innovative flu vaccines in the U.S.

The details

The FDA's vaccine director, Dr. Vinay Prasad, said the agency doesn't consider Moderna's trial to be an 'adequate and well-controlled' study because it didn't compare the new shot to 'the best-available standard of care' for seniors. Moderna said it had shared additional data comparing the new vaccine to a licensed high-dose shot for seniors, but the FDA still refused to file the application.

  • Moderna received the 'refusal-to-file' letter from the FDA on February 11, 2026.
  • In 2024, under the Biden administration, the FDA provided Moderna with feedback on the clinical trial design, which the company did not follow.

The players

Moderna

An American biotechnology company that develops vaccines and therapeutics, including a new mRNA-based flu vaccine.

U.S. Food and Drug Administration (FDA)

The federal agency responsible for regulating and supervising the safety of food, drugs, and medical devices in the United States.

Robert F. Kennedy Jr.

The current U.S. Secretary of Health and Human Services, who has been critical of vaccines, particularly those using mRNA technology.

Dr. Vinay Prasad

The director of the FDA's vaccine division, who issued the 'refusal-to-file' letter to Moderna.

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What they’re saying

“The FDA 'did not identify any safety or efficacy concerns with our product' and 'does not further our shared goal of enhancing America's leadership in developing innovative medicines,'”

— Stephane Bancel, CEO of Moderna (Boston.com)

What’s next

Moderna has requested an urgent meeting with the FDA to discuss the decision and noted that it has applied for the vaccine's approval in Europe, Canada and Australia.

The takeaway

This decision highlights the FDA's heightened scrutiny of vaccines, especially those using mRNA technology, under the leadership of Health Secretary Robert F. Kennedy Jr. It could impact the development and availability of innovative flu vaccines in the U.S. and raises questions about the agency's approach to evaluating new vaccine technologies.