The U.S. Food and Drug Administration has rejected Moderna’s submission for a novel flu vaccine utilizing Nobel Prize-winning mRNA technology, as disclosed by the company on Tuesday. This development reflects the FDA’s increased scrutiny of vaccines during Health Secretary Robert F. Kennedy Jr.’s tenure, particularly those employing mRNA technology, which he has criticized both before and after assuming his role as the nation’s top health official.
Moderna received a “refusal-to-file” notification from the FDA, citing concerns over the methodology of a 40,000-participant clinical trial comparing its new vaccine to a standard flu shot currently in use. The trial indicated that the new vaccine showed slightly better efficacy in adults aged 50 and above compared to the existing shot.
According to the FDA’s vaccine director, Dr. Vinay Prasad, the agency deemed the application lacking an “adequate and well-controlled trial” as it did not compare the new vaccine to the best-available standard of care in the U.S. at the time. The letter referenced guidance given to Moderna in 2024 under the previous administration, which the company did not fully adhere to.
Despite some differences in approach, Moderna proceeded with the study as planned after receiving FDA approval. The company also submitted additional data from a separate trial comparing the new vaccine with a licensed high-dose shot commonly used for seniors. Moderna’s CEO, Stephane Bancel, stated that the FDA did not raise any safety or efficacy concerns regarding their product.
The FDA’s decision to refuse the application, a rare occurrence, necessitates further dialogue between Moderna and the regulatory agency, with the company also seeking approval for its vaccine in Europe, Canada, and Australia. Under Kennedy’s leadership, several changes have been implemented, such as revising recommendations for COVID-19 vaccines, including additional warnings on mRNA-based vaccines, and reshaping the FDA advisory panel by removing dissenting voices.
Kennedy’s department previously revealed the cancellation of over $500 million in contracts and funding for mRNA vaccine development. Historically, the FDA has allowed vaccine manufacturers to swiftly update annual flu vaccines to target prevalent strains by demonstrating their ability to trigger an immune response, a more efficient process than lengthy studies monitoring flu incidence and outcomes in patients.
An internal memo from Prasad signaled a shift away from this streamlined approach, prompting criticism from numerous former FDA commissioners in an editorial condemning the decision.