The announcement made by Moderna on Tuesday revealed that the U.S. Food and Drug Administration has declined to review the company’s application for a new flu vaccine utilizing Nobel Prize-winning mRNA technology. This decision reflects the FDA’s increased scrutiny of vaccines during Health Secretary Robert F. Kennedy Jr.’s tenure, especially those incorporating mRNA technology, which he has criticized.
Moderna received a “refusal-to-file” letter from the FDA regarding a 40,000-person clinical trial comparing its innovative vaccine to a standard flu shot. Although the trial demonstrated the new vaccine’s higher effectiveness in adults aged 50 and above, the FDA raised concerns about the trial’s design not adequately comparing the new shot to the best-available standard flu shot in the U.S. at the time.
Dr. Vinay Prasad, FDA’s vaccine director, highlighted that the application lacked an “adequate and well-controlled trial” as per FDA standards, referencing guidance provided to Moderna in 2024 that was not fully followed. Despite this, the FDA permitted the study to proceed with the originally selected standard-dose flu shot.
Moderna stated that the FDA did not raise any safety or efficacy issues with their product, and CEO Stephane Bancel confirmed the submission of additional data from a separate trial comparing the new vaccine with a licensed high-dose shot for seniors.
The FDA’s refusal to review the application is uncommon, especially in the case of a new vaccine, necessitating prolonged discussions between companies and FDA officials. Moderna has expressed the urgency of meeting with the FDA and has also sought approval for the vaccine in Europe, Canada, and Australia.
Under Kennedy’s leadership, significant changes have been observed in vaccine recommendations and warnings, particularly concerning mRNA technology-based COVID-19 vaccines. The FDA’s approach has faced criticism, with concerns raised over the removal of critics from advisory panels.
Kennedy’s decision last year to withdraw over $500 million in funding for mRNA vaccine development has had far-reaching implications. The FDA’s traditional approach of allowing rapid updates to flu shots based on immune response rather than long-term studies has come under scrutiny, with a shift in regulatory stance prompting backlash from former FDA commissioners.
