In a significant regulatory development, Moderna announced Tuesday that the U.S. Food and Drug Administration has declined to review the company’s application for an innovative mRNA-based influenza vaccine. The decision represents the latest indication of intensified FDA oversight under Health Secretary Robert F. Kennedy Jr., who has consistently expressed skepticism toward mRNA technology both before and after assuming his current position.
The FDA issued a ‘refusal-to-file’ letter citing concerns about Moderna’s clinical trial design, which involved 40,000 participants comparing the new vaccine against a standard flu shot. While the study demonstrated superior efficacy in adults aged 50 and older, FDA vaccine director Dr. Vinay Prasad determined the application lacked an ‘adequate and well-controlled trial’ because it didn’t compare the vaccine to ‘the best-available standard of care in the United States at the time of the study.’
According to Moderna, FDA officials under the Biden administration had provided 2024 guidance indicating that while another brand specifically recommended for seniors would be preferable for participants aged 65 and older, the company’s chosen standard-dose vaccine remained acceptable. Moderna proceeded with the original study design with FDA’s conditional approval.
The company emphasized that the FDA identified no specific safety or efficacy concerns with their product and noted they had submitted additional data from a separate trial comparing the vaccine against a licensed high-dose shot for elderly patients. Moderna CEO Stephane Bancel stated the decision ‘does not further our shared goal of enhancing America’s leadership in developing innovative medicines.’
This regulatory action occurs against a backdrop of significant policy shifts under Kennedy’s leadership, including the rollback of COVID-19 shot recommendations, additional warnings for leading mRNA COVID vaccines, and the removal of administration critics from FDA advisory panels. Kennedy previously announced the cancellation of over $500 million in contracts and funding for mRNA vaccine development.
The refusal marks a departure from decades of FDA practice allowing vaccine manufacturers to update annual flu shots based on immune response data rather than long-term efficacy studies. Prasad’s internal memo last year indicated this streamlined approach would no longer be permitted, prompting criticism from more than a dozen former FDA commissioners.
Moderna has requested an urgent meeting with the FDA while pursuing regulatory approval for the vaccine in Europe, Canada, and Australia.