KEY POINTS
- The U.S. FDA has refused to review Moderna’s application for its mRNA influenza vaccine.
- The agency said the clinical trial data lacked an adequate comparator for U.S. standards.
- Moderna says the refusal isn’t linked to safety or effectiveness concerns and seeks a meeting with regulators.
Moderna said the U.S. Food and Drug Administration will not review its application for an mRNA-based influenza vaccine. The company announced the refusal under a “refuse-to-file” decision from the regulator.
The FDA’s notice cited the design of Moderna’s pivotal trials as the reason for the refusal. The regulator said the studies were not “adequate and well-controlled” because they lacked the most appropriate comparator vaccine.
Moderna’s experimental vaccine, known as mRNA-1010, was tested against a standard seasonal flu shot in late-stage trials. The company reported the vaccine showed greater effectiveness than the comparator in those studies. However, the FDA said those data did not meet its requirements for review.
The regulator did not cite any safety or efficacy issues with the vaccine in its refusal letter. Moderna said the lack of safety or performance concerns underscores its belief in the vaccine’s promise.
CEO Stephane Bancel criticized the FDA’s decision as inconsistent with prior communications from the agency. He said the refusal could hinder innovation in vaccine development.
Moderna said it plans to request a meeting with the FDA to chart a path forward. The company hopes to address the regulator’s concerns and resubmit or modify its application.
Despite the U.S. setback, Moderna continues to pursue approval of the vaccine in other markets. Regulators in the European Union, Canada and Australia are currently reviewing similar data.
Shares of Moderna fell sharply in after-hours trading following the announcement. The stock reaction reflected investor concern over delayed access to the U.S. influenza market.
The FDA’s refusal comes amid broader regulatory shifts in U.S. vaccine oversight and approval standards. Some observers view the decision as part of evolving expectations for clinical trials and comparator use.
Under long-standing policy, influenza vaccines often require demonstration of immune response rather than direct comparisons with other products. In this case, the agency determined Moderna’s trial did not align with the best-available standard of care in the United States.
Moderna has emphasized that its trial design was discussed with FDA staff before initiation. The company said it submitted additional analyses comparing its vaccine to a high-dose option used for older adults.
Industry experts say the FDA’s decision could impact future applications for mRNA-based flu shots. The development may prompt companies to re-evaluate study designs to meet updated regulatory expectations.
Moderna’s vaccine uses mRNA technology similar to its COVID-19 products. The firm and other developers see mRNA platforms as key to next-generation flu protection.
The refusal highlights challenges for novel vaccine candidates in the U.S. market. How Moderna proceeds with regulators and future trial designs will influence the timing of approval.
