Moderna says FDA refuses its application for new mRNA flu vaccine

The FDA has refused to consider Moderna's application for its new mRNA flu vaccine. The FDA issued a "refusal-to-file" letter objecting to Moderna's 40,000-person clinical trial, which compared the new vaccine to a standard flu shot and found it more effective in adults 50 and older. FDA vaccine director Dr. Vinay Prasad stated the trial was inadequate because it didn't compare the new shot to the best available standard of care in the US at the time of the study. The FDA pointed to advice given to Moderna in 2024 under the Biden administration, which Moderna didn't follow, regarding the use of a specific flu shot for seniors. Moderna claims the FDA initially agreed to the study's design.

The FDA has declined to review Moderna's application for a new mRNA flu vaccine, despite previously signaling approval for the project. The FDA's decision stems from concerns that Moderna's clinical trials compared the new shot to standard flu shots instead of high-dose vaccines for high-risk individuals, deeming the trials inadequate. Moderna did compare their vaccine against an existing high-dose flu shot in adults ages 65 and older. Experts worry this decision could discourage future investment in innovative influenza vaccines and create uncertainty for vaccine development. While Moderna's trials showed the new vaccine elicited better antibody responses than existing vaccines, the FDA issued a refusal-to-file letter, requiring more information before considering the application.