The US FDA has belatedly accepted the Biologics License Application (BLA) for Moderna’s investigational seasonal influenza vaccine, mRNA-1010, for review. The company is seeking approval for the prevention of influenza in adults aged 50 years and older. This follows a procedural setback earlier this month, where the agency initially issued a Refusal-to-File letter regarding the application. Following a subsequent Type A meeting to resolve the agency’s feedback, the FDA has assigned a Prescription Drug User Fee Act (PDUFA) goal date of August 5, 2026. If approved, mRNA-1010 would be the first mRNA-based seasonal influenza vaccine to enter the US market, marking a significant technological shift from the conventional egg-based and cell-based manufacturing platforms currently in use.
The BLA outlines a split regulatory pathway based on patient age. Moderna is pursuing full approval for adults aged 50 to 64 years and accelerated approval for adults aged 65 years and older. The accelerated approval pathway typically allows for earlier clearance of drugs that treat serious conditions and fill an unmet medical need based on a surrogate endpoint, such as immunogenicity, pending verification of clinical benefit in post-marketing trials. Accordingly, the filing includes a post-marketing requirement for Moderna to conduct a confirmatory study in the older adult population. While full prescribing information is not yet public, the vaccine is administered as a single intramuscular injection, consistent with standard seasonal influenza immunization schedules.
The FDA’s initial refusal to file the BLA centered on a disagreement regarding the clinical trial’s control arm for older participants. In the pivotal P304 trial, Moderna compared mRNA-1010 to a licensed standard-dose influenza vaccine. However, for adults aged 65 and older, the US CDC preferentially recommends “enhanced” vaccines—such as high-dose or adjuvanted options—to compensate for age-related immune decline. CBER Director Dr. Vinayak Prasad asserted that the use of a standard-dose comparator for this specific demographic failed to reflect the “best-available standard of care,” rendering the study’s design inadequate for a standard review. Moderna contested this, noting that the agency had previously categorized a standard-dose comparator as “acceptable” in 2024 and that existing federal regulations do not explicitly mandate “best-available” controls for approval. The split regulatory pathway for mRNA-1010 appears to be the solution to that impasse, balancing standard evidence requirements with the accelerated needs of the senior population.