CBER Issues RTF for Moderna’s Investigational Flu Shot
According to Moderna, the reasoning for the refusal to review the BLA by the regulatory authority is inconsistent with previous feedback, leading the company to request a Type A meeting.
The U.S. FDA’s Center for Biologics Evaluation and Research (CBER) has issued a refusal-to-file (RTF) letter for Moderna’s biologics license application of mRNA-1010 —its investigational influenza vaccine. This decision from the regulatory authority is inconsistent with previous feedback received during pre-Phase III and pre-submission consultations, the company reports (1).
Signed by CBER Director, Vinayak Prasad, MD, MPH, the RTF letter specifically points to the choice of a licensed standard-dose seasonal influenza vaccine comparator as the reason for its refusal to initiate the application review. As specified in the letter, published in full on Moderna’s website by the company (2), the regulator stated: “CBER does not consider the application to contain a trial ‘adequate and well-controlled’ and the application is therefore, on its’ face, inadequate for review. This is because your control arm does not reflect the best-available standard of care in the United States at the time of the study.”
While the CBER’s letter asserts that the refusal decision is consistent with prior regulatory advice, Moderna has highlighted written guidance from CBER in 2024 whereby the study plans were agreed upon and no objections were made by the regulator. Additionally, the company has pointed to feedback from CBER in 2025, after the successful completion of a Phase III efficacy trial on the vaccine, that requested supportive analyses on the comparator be provided, which Moderna had included in its submission (1).
"This decision by CBER, which did not identify any safety or efficacy concerns with our product, does not further our shared goal of enhancing America's leadership in developing innovative medicines," said Stéphane Bancel, Chief Executive Officer of Moderna, in a company press release (1). "It should not be controversial to conduct a comprehensive review of a flu vaccine submission that uses an FDA-approved vaccine as a comparator in a study that was discussed and agreed on with CBER prior to starting. We look forward to engaging with CBER to understand the path forward as quickly as possible so that America's seniors, and those with underlying conditions, continue to have access to American-made innovations."
Following on from the CBER’s RTF letter, Moderna has requested a Type A meeting with the regulator to understand the reasoning for the refusal to review the BLA. Regulatory applications for the vaccine have been accepted for review in the European Union, Canada, and Australia already, with the company expecting to submit further applications in other countries during the course of 2026.
While the company does not expect the RTF to impact its 2026 financial guidance, stock value had dropped by 6.4% following the announcement (3).
References
Moderna. Moderna Receives Refusal-to-File Letter from the U.S. Food and Drug Administration for Its Investigational Seasonal Influenza Vaccine, mRNA-1010. Press Release, Feb. 10, 2026.
Moderna. Center for Biologics Evaluation and Research Refusal to File Letter — mRNA-1010. Modernatx.com, accessed Feb. 10, 2026.
Gatlin, A. Moderna Plunges After FDA Rejects its Messenger-RNA-Based Flu Shot. Investor’s Business Daily, Feb. 10, 2026.