The FDA rejected Moderna’s mRNA flu vaccine application, citing an outdated comparator, despite positive trial results.

The U.S. FDA has refused to review Moderna’s application for its mRNA flu vaccine, mRNA-1010, citing the use of a standard-dose seasonal flu vaccine as a comparator, which the agency said did not reflect the best-available standard of care. The decision, delivered via a Refusal-to-File letter, did not raise safety or efficacy concerns but contradicts prior FDA feedback that approved the trial design. Moderna, which reported positive results in late-stage trials showing greater effectiveness than a GSK vaccine, expressed surprise and plans to request a meeting to clarify the FDA’s rationale. The vaccine remains under review in the EU, Canada, and Australia, with potential approvals expected in late 2026 or early 2027.