Moderna Says FDA Refuses to Review Its Application for Experimental Flu Shot

Why It Matters

The refusal delays a potentially lucrative mRNA flu vaccine and signals tighter regulatory scrutiny that could affect Moderna’s pipeline and broader vaccine innovation.

Key Takeaways

• FDA declined to review Moderna's mRNA‑1010 flu vaccine.
• Review refusal based on trial comparator design, not safety.
• Moderna's shares dropped about 7% after announcement.
• Approval now projected for late 2026 or 2027.
• Regulatory stance reflects heightened vaccine scrutiny under new leadership.

Pulse Analysis

Moderna’s mRNA‑1010 flu shot entered phase‑three trials with promising results, meeting all predefined efficacy endpoints. The vaccine leverages the same messenger‑RNA platform that propelled the company’s COVID‑19 products, positioning it as a next‑generation seasonal flu solution. Analysts had anticipated a swift regulatory pathway, given the data package and prior FDA interactions, which would have expanded Moderna’s portfolio beyond pandemic response into routine immunizations.

The FDA’s refusal to initiate a review stems from a dispute over the study’s comparator arm. Agency officials argued that using an existing approved flu vaccine as the control did not represent the "best‑available standard of care," a stance championed by CBER head Vinay Prasad. While the agency did not flag safety or efficacy concerns, the procedural objection reflects a broader shift toward more stringent trial designs under the current health leadership, echoing recent policy changes that have tightened vaccine oversight.

For Moderna, the setback postpones potential revenue from a high‑margin flu product and adds uncertainty to its 2026 financial outlook, though the company maintains guidance remains intact. The delay also underscores the importance of aligning trial designs with evolving regulatory expectations, a lesson that could influence future mRNA ventures, including combination COVID‑flu candidates. Investors and industry watchers will monitor how quickly Moderna can resolve the FDA’s concerns, as the outcome may set a precedent for other mRNA‑based vaccines seeking market entry.

Moderna says FDA refuses to review its application for experimental flu shot

By Annika Kim Constantino · Published Tue, Feb 10 2026 6:03 PM EST

• The Food and Drug Administration has refused to start a review of Moderna’s application for its experimental flu shot, the company said.

• It’s another sign of the Trump administration’s influence on tightening vaccine regulation in the U.S.

• Moderna said the move is inconsistent with previous feedback the FDA gave before it submitted the application and started phase‑three trials on the shot, called mRNA‑1010, and that the agency did not identify any specific safety or efficacy issues with the vaccine.

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A researcher works in the lab at the Moderna Inc. headquarters in Cambridge, Massachusetts, US, on Tuesday, March 26, 2024.

Adam Glanzman | Bloomberg | Getty Images

The Food and Drug Administration has refused to start a review of Moderna’s application for its experimental flu shot, the company announced Tuesday, in another sign of the Trump administration’s influence on tightening vaccine regulations in the U.S.

The company’s stock fell roughly 7 % in after‑hours trading Tuesday.

Moderna said the move is inconsistent with previous feedback from the agency before it submitted the application and started phase‑three trials on the shot, called mRNA‑1010. The drugmaker said it has requested a meeting with the FDA to “understand the path forward.”

Moderna noted that the agency did not identify any specific safety or efficacy issues with the vaccine, but instead objected to the study design, despite previously approving it. The company added that the move won’t impact its 2026 financial guidance.

Moderna’s jab showed positive phase‑three data last year, meeting all of the trial goals. At the time, Moderna said the stand‑alone flu shot was key to its efforts to advance a combination vaccine targeting both influenza and Covid‑19.

The announcement follows sweeping changes to U.S. immunization policy over the past year under Health and Human Services Secretary Robert F. Kennedy Jr., a prominent vaccine skeptic.

Moderna on Tuesday specifically pointed to the FDA’s top vaccine regulator, Vinay Prasad, who returned to the agency in August after being ousted. Prasad, who heads the agency’s Center for Biologics Evaluation and Research (CBER), has been vocal about tightening regulations for vaccines and recently linked child deaths to Covid shots.

In a letter signed by Prasad on Feb. 3, he said the sole reason why the FDA refused to review the application was because of how the clinical trial on the shot was designed. The agency specifically took issue with Moderna’s decision to compare its product to a standard, approved flu shot, arguing that it “does not reflect the best‑available standard of care.” As a result, the FDA said the study did not meet its definition of an “adequate and well‑controlled” trial.

Moderna disputes that reasoning, noting that FDA rules and guidance do not actually require trials to use the most advanced or highest‑dose vaccine as a comparator in clinical studies.

“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,” Moderna CEO Stéphane Bancel said in a release. “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.”

Moderna said it expects the earliest approval for its flu shot to be in late 2026 or late 2027, pending regulatory reviews in the U.S., Europe, Canada and Australia.

The FDA said it does not comment on regulatory communications to individual sponsors.