WASHINGTON: The U.S. Food and Drug Administration has agreed to begin reviewing an amended application from Moderna for its investigational mRNA-based seasonal influenza vaccine, mRNA-1010, reversing an earlier decision not to take up the filing. Moderna said the FDA’s Center for Biologics Evaluation and Research accepted the amended biologics license application for review and set a Prescription Drug User Fee Act goal date of Aug. 5, 2026.
The company disclosed on Feb. 10 that CBER had issued a Refusal-to-File letter stating it would not initiate review of the original application. Moderna said the letter, signed by CBER Director Vinayak Prasad, cited a single issue: the use of a licensed standard-dose seasonal influenza vaccine as the comparator for participants older than 65 in a pivotal study, which the agency said did not reflect the best-available standard of care. Moderna said the letter did not identify specific safety or efficacy concerns with mRNA-1010.
Moderna said it subsequently met with CBER in a Type A meeting and submitted an amended application built around an age-based regulatory approach. Under that approach, Moderna is seeking full approval for adults ages 50 to 64 and accelerated approval for adults 65 and older, with a post-marketing requirement to conduct an additional study in the older population. Moderna said the FDA accepted the amended application and started the review process under the Aug. 5, 2026 goal date.
Clinical evidence in the filing
Moderna said its submission is supported by two Phase 3 studies that enrolled a total of 43,808 participants and met pre-specified primary endpoints. In the company’s description, P303 Part C was a safety and immunogenicity study comparing mRNA-1010 with a licensed high-dose influenza vaccine comparator in adults 65 and older. Moderna said P304 was a safety and relative efficacy study comparing mRNA-1010 with a licensed standard-dose influenza vaccine comparator in adults 50 and older, and that primary endpoints in both Phase 3 studies showed statistical superiority of mRNA-1010 versus their respective comparators.
The company said its Phase 3 designs were reviewed by the FDA before study initiation. Moderna also cited prior written feedback from CBER during a pre-Phase 3 consultation in April 2024 stating it would be acceptable to use a licensed standard-dose influenza vaccine as the comparator, while recommending an influenza vaccine preferentially recommended for older adults by the Advisory Committee on Immunization Practices for participants older than 65. Moderna said CBER did not place a clinical hold or otherwise object to the adequacy of the Phase 3 trial before the study began in September 2024.
Comparator standards for older adults
Current ACIP guidance summarized by the Centers for Disease Control and Prevention recommends that adults ages 65 and older preferentially receive one of three vaccine types when available: high-dose inactivated influenza vaccine, recombinant influenza vaccine, or adjuvanted inactivated influenza vaccine. The Feb. 10 Refusal-to-File letter described by Moderna centered on whether the trial’s control arm for older adults used a comparator aligned with that preference. Moderna said it provided additional analyses in its submission, including data from the Phase 3 P303 Part C study that used a licensed high-dose comparator in adults 65 and older.
Moderna, which is based in Cambridge, Massachusetts, said mRNA-1010 has also been accepted for review in Europe, Canada and Australia. Moderna shares closed up 6% on Feb. 18 after the company announced the FDA would proceed with reviewing the amended application, and the agency’s goal date for acting on the filing is Aug. 5, 2026 – By Content Syndication Services.