FDA Halts Moderna’s New mRNA Flu Vaccine: What This Means for the Future of Vaccination

WASHINGTON – Moderna announced on Tuesday that the U.S. Food and Drug Administration (FDA) has declined to review its application for a new influenza vaccine utilizing the innovative mRNA technology, which has been recognized with a Nobel Prize.

This development marks a continuation of the FDA’s increased scrutiny of vaccines under the leadership of Health Secretary Robert F. Kennedy Jr. Kennedy has expressed skepticism about mRNA technology, both prior to and following his appointment as the nation’s leading health official.

The FDA issued a “refusal-to-file” letter to Moderna, citing concerns about the methodology of a 40,000-participant clinical trial. The trial compared Moderna’s new vaccine to a commonly used flu shot, finding the new vaccine to be somewhat more effective in adults aged 50 and above.

In the refusal letter, Dr. Vinay Prasad, the FDA’s director of vaccines, stated that the application lacked an “adequate and well-controlled trial.” The main issue was that the trial did not compare the new vaccine against the “best-available standard of care in the United States at the time of the study.” Dr. Prasad referenced recommendations given to Moderna in 2024 during the Biden administration, which the company did not fully adhere to.

Moderna explained that the FDA had initially agreed to the use of a standard-dose flu shot for the trial. However, the agency had indicated that a different brand, specifically recommended for seniors, would be preferable for participants aged 65 and older. Despite this, the FDA permitted Moderna to proceed with the study as initially designed.

The company said it also had shared with FDA additional data from a separate trial comparing the new vaccine against a licensed high-dose shot used for seniors.

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,” Moderna CEO Stephane Bancel said in a statement.

It’s rare that FDA refuses to file an application, particularly for a new vaccine, which requires companies and FDA staff to engage in months or years of discussions.

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

In the last year, FDA officials working under Kennedy have rolled back recommendations around COVID-19 shots, added extra warnings to the two leading COVID vaccines — which are made with mRNA technology — and removed critics of the administration’s approach from an FDA advisory panel.

Kennedy announced last year that his department would cancel more than $500 million in contracts and funding for the development of vaccines using mRNA.

FDA for decades has allowed vaccine makers to quickly update their annual flu shots to target the latest strains by showing that they trigger an immune response in patients. That’s a far more efficient approach than running long-term studies tracking whether patients get the flu and how they fare. In an internal memo last year, Prasad wrote that the streamlined method would no longer be permitted – leading more than a dozen former FDA commissioners to pen an editorial condemning the statements.

—-

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.