FDA Rejects Moderna’s Flu Vaccine Due to Comparator Choice | Ars Technica

February 11, 2026 Rachel Kim – Technology Editor Technology

The Food and Drug Administration (FDA) has declined to review Moderna’s application for its mRNA-based flu vaccine, a move that has prompted the company to seek clarification from the agency. The decision, communicated in a letter dated February 3, centers on the FDA’s assessment of the clinical trial design.

According to Moderna, the FDA determined the trial was not “adequate and well-controlled” because the comparator vaccine used in the study did not represent the “best-available standard of care.” This assessment, however, is contested by Moderna, which stated in a press release that neither the FDA’s regulations nor its industry guidance explicitly require a comparator vaccine to meet that standard.

“This decision by [the FDA’s Center for Biologics Evaluation and Research], 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 the release. Bancel further emphasized that the trial protocol, which utilized an FDA-approved vaccine as a comparator, had been discussed and agreed upon with the FDA’s Center for Biologics Evaluation and Research (CBER) prior to the study’s commencement.

The FDA’s decision comes as Moderna seeks to expand its mRNA technology beyond COVID-19 vaccines. The company’s mRNA-1010 flu vaccine candidate has already been accepted for review by regulatory bodies in the European Union, Canada, and Australia, highlighting the differing regulatory approaches to the novel vaccine technology.

Moderna has requested a meeting with the FDA to discuss the basis for the refusal and to determine a path forward for the application. The company stated its intention to continue pursuing approval for the vaccine, particularly to ensure access for seniors and individuals with underlying health conditions. The company is hoping to resolve the issue quickly, according to their statement.