FDA Accepts Moderna Flu Vaccine Filing After Swift Rethink

The FDA reversed course and accepted Moderna's revised mRNA flu vaccine application just eight days after a refusal, with an August 2026 decision deadline.

The U.S. Food and Drug Administration has accepted Moderna's amended application for its mRNA influenza vaccine, mRNA-1010, just over one week after issuing a surprise refusal-to-file letter that sent the biotech's shares tumbling . The rapid turnaround follows a constructive Type A meeting between the company and regulators, resolving a dispute centered entirely on trial design for older adults.

Under the compromise, Moderna will pursue a dual regulatory pathway: full approval for adults aged 50 to 64 years, and accelerated approval for those 65 and older. The company has also committed to conducting a post-marketing study in seniors once the vaccine becomes available. The FDA set a Prescription Drug User Fee Act goal date of August 5, 2026, positioning mRNA-1010 for potential availability during the upcoming flu season.

The initial February 10 refusal, signed by FDA vaccine Chief Dr. Vinay Prasad, cited the lack of a "best-available standard of care" comparator for seniors. While the CDC's Advisory Committee on Immunization Practices recommends high-dose or adjuvanted vaccines for adults 65 and older, Moderna's Phase 3 efficacy study used a standard-dose comparator. The company noted the FDA had previously agreed to this design in 2024 and had submitted requested high-dose data separately.

Industry analysts characterized the episode as an "about-face" that restores a significant potential revenue stream for Moderna, with shares rebounding over 6% on the news. If approved, mRNA-1010 would become the first mRNA-based flu vaccine available for older adults, though traditional options would remain.