FDA Declines to Review Moderna's Flu Vaccine Application, Citing Trial Design

Moderna announced Tuesday that the U.S. Food and Drug Administration has declined to formally review the company's application for its experimental influenza vaccine, mRNA-1010. The decision sent the company's shares down approximately 7% in after-hours trading.

According to Moderna, the FDA's refusal centers on the design of the vaccine's Phase 3 clinical trial, which compared the new mRNA shot to a standard, already-approved flu vaccine. The agency stated this comparator did not reflect the "best-available standard of care," and therefore the study was not considered "adequate and well-controlled." Moderna contests this, arguing that its trial design was previously discussed with the FDA and that agency rules do not mandate using the most advanced comparator.

The company emphasized the FDA identified no specific safety or efficacy problems with the vaccine itself, which met all its Phase 3 goals last year. Moderna has requested a meeting with the agency to clarify a path forward. The setback does not affect the company's 2026 financial guidance, but it could delay the shot's earliest possible U.S. approval to late 2026 or 2027.

The move occurs within a broader context of tightened vaccine oversight. The FDA's top vaccine regulator, Vinay Prasad, who leads the Center for Biologics Evaluation and Research (CBER), signed the February 3rd letter detailing the decision. Prasad, who returned to the agency last August, has publicly advocated for stricter vaccine regulations. The regulatory environment has shifted under Health and Human Services Secretary Robert F. Kennedy Jr., a noted vaccine skeptic.

In a statement, Moderna CEO Stéphane Bancel expressed disappointment, saying the decision does not advance the shared goal of U.S. leadership in medical innovation. The FDA declined to comment on the matter.

Source: CNBC