The U.S. Food and Drug Administration has declined to review Moderna’s request for authorization of a novel flu vaccine utilizing Nobel Prize-winning mRNA technology, the firm revealed on Tuesday. This development reflects the FDA’s increased scrutiny of vaccines during Health Secretary Robert F. Kennedy Jr.’s tenure, especially those employing mRNA technology, which he has criticized both before and after assuming his role as the nation’s top health official.
Moderna was issued a “refusal-to-file” communication from the FDA, citing concerns with the methodology of a 40,000-person clinical trial that compared the efficacy of its new vaccine against a standard flu shot currently in use. The trial indicated that the new vaccine was marginally more effective in adults aged 50 and above than the standard shot.
FDA vaccine director Dr. Vinay Prasad’s letter highlighted that the agency did not view the application as having an “adequate and well-controlled trial” as it failed to compare the new vaccine with the “best-available standard of care in the United States at the time of the study.” The letter referenced advice given to Moderna in 2024, during the Biden administration, which the company did not adhere to.
Moderna stated that the FDA had approved the study to proceed as initially planned, despite feedback suggesting an alternative flu shot for seniors would be preferable for participants aged 65 and older. The company also provided additional data from a separate trial comparing its new vaccine with a licensed high-dose shot for seniors.
Moderna’s CEO, Stephane Bancel, asserted that the FDA did not raise any safety or efficacy concerns regarding their product. The company is seeking an urgent meeting with the FDA and has submitted the vaccine for approval in Europe, Canada, and Australia.
Under Kennedy’s leadership, regulatory changes have been made regarding COVID-19 vaccines, including enhanced warnings on mRNA-based COVID vaccines and the removal of critics from an FDA advisory panel. Kennedy had previously announced the cancellation of over $500 million in funding for the development of mRNA vaccines.
The FDA traditionally permits vaccine manufacturers to swiftly update their annual flu vaccines to target prevailing strains by demonstrating their ability to elicit an immune response, a more efficient approach compared to lengthy studies monitoring flu incidence and outcomes in patients. In a recent internal memo, Prasad indicated a shift away from this streamlined method, prompting criticism from numerous former FDA commissioners.
This decision by the FDA to decline Moderna’s application is a rare occurrence, particularly for a new vaccine, necessitating prolonged discussions between companies and FDA officials.