FDA Refuses to Review Moderna’s mRNA Influenza Shot License Application

The U.S. Food and Drug Administration (FDA) has declined to accept for review Moderna’s Biologics License Application (BLA) for its mRNA-based seasonal influenza shot, citing concerns about the completeness of the submission. The decision highlights the agency’s commitment to maintaining clear evidentiary standards for approving the licensing of new vaccines.¹

On Feb. 3, 2026, the FDA issued Moderna a formal “Refusal to File” letter for its biologics license application for the flu shot known as mRNA-1010. The agency said the submission did not include enough information for FDA officials to proceed with a full review of the product’s safety and effectiveness. This decision was based on an initial administrative check to determine whether the application met basic filing requirements, not on a detailed scientific evaluation of the mRNA biologic. Since those filing requirements were not met, the FDA said it could not begin a full review.²

Clinical Trial Design Issues Led to the FDA’s Refusal to File

The FDA’s decision focused on the design of Moderna’s Phase 3 clinical trial. The agency stated that the study was not “adequate and well-controlled” because the control arm did not reflect the appropriate standard of care for the intended population.³

The agency said it raised specific concerns about the  flu vaccine used in the control arm of the clinical trial for participants aged 65 and older. People in this age group face a higher risk of serious influenza disease complications, and a high-dose flu vaccine is currently licensed and recommended for them.

Instead of using the high dose flu vaccine licensed for seniors as a control in the trial, Moderna used Fluarix Quadrivalent, a flu vaccine manufactured by GlaxoSmithKline (GSK). While the FDA has approved Fluarix Quadrivalent for use in the United States, the U.S. Centers for Disease Control and Prevention (CDC) does not recommend it for seniors aged 65 and older.⁴

A senior FDA official said the agency questioned Moderna’s choice of the control vaccine and suggested the decision may have been intentional, potentially making the company’s mRNA influenza shot appear more effective when compared with a flu shot that is not routinely recommended for seniors.⁵

You can either do what’s right, and give seniors the standard of care that best protects them the best, or you can kind of rig the study so it makes your product look better. This is not a Moderna unique issue, this is an issue that has gone on at the FDA for decades.⁶

FDA commissioner Marty Makary, MD, MPH note
The FDA official said:d that the trial did not use the high-dose flu vaccine for some older participants. He said:

Some say that the trial that they conducted was unethical for not offering the best option as a control for seniors.⁷

FDA Explains Its Decision as Moderna Pushes Back

The FDA defended its decision publicly, explaining that refusing to review an incomplete application helps preserve the integrity of the vaccine approval process. Officials said the step ensures that products moving forward meet high  scientific and regulatory benchmarks. FDA officials also stated that the refusal does not prevent Moderna from resubmitting an application in the future if the company addresses the agency’s concerns.⁸

Moderna disputed that characterization and said it held a series of meetings with the FDA beginning in April 2024, during which agency officials agreed to a study plan that compared the mRNA shot with  GSK’s Fluarix. Chris Ridley, a spokesperson for Moderna, said the company understood the trial design to be acceptable to the agency. He said the FDA’s communications indicated that Moderna could proceed with the study as planned.⁹

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