FDA Reverses Course, Will Review Moderna’s mRNA Flu Vaccine
The U.S. Food and Drug Administration (FDA) will now review Moderna’s novel, messenger RNA (mRNA)-based flu vaccine after reversing its initial decision, a move that significantly impacts the biopharmaceutical industry. The reversal comes after Moderna proposed a revised regulatory approach for its investigational seasonal influenza vaccine candidate, mRNA-1010.
Shift in Regulatory Strategy
Initially, Moderna sought standard FDA approval for the flu shot for all adults aged 50, and older. However, the company has now amended its approach, seeking traditional full approval for adults aged 50-64 and accelerated approval for those 65 and older. Accelerated approval for the older age group will be contingent upon a post-marketing requirement to conduct an additional study specifically focused on this population. CIDRAP
Concerns Over Phase 3 Trial Design
The FDA’s initial reluctance stemmed from concerns regarding the comparator arm used in Moderna’s Phase 3 clinical trial. FDA’s Center for Biologics Evaluation and Research (CBER) director, Dr. Vinay Prasad, questioned the leverage of a standard-dose flu shot as the comparison in the trial for individuals aged 65 and older, suggesting a higher-dose flu vaccine would have been more appropriate, reflecting the current standard of care in the United States. STAT News
Unusual FDA Action and Industry Reaction
Dr. Prasad’s decision to issue a “refuse-to-file” letter – a rare action for a CBER director – surprised many in the industry. Typically, such decisions are made by lower-level staff. Refusing to review the application altogether is not standard practice when disagreements arise over study protocols; these are usually addressed during the FDA review process or through advisory committee discussions. STAT News
Moderna’s Response and FDA Engagement
Moderna maintained that the FDA had not previously raised concerns about the Phase 3 study design. “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,” said CEO Stéphane Bancel in a previous statement. STAT News The FDA has accepted the application for review, with a deadline of August 5, 2026. CIDRAP
Broader Implications and FDA Uncertainty
Despite the reversal, the situation has created uncertainty within the biopharmaceutical industry. Reports suggest Dr. Prasad has overruled agency staff on multiple occasions and contributed to the departure of career drug reviewers. This has led to concerns about a “chaotic environment” within the FDA, with some staff actively seeking employment elsewhere. NPR
Analysts have described the situation as “regulatory whiplash,” noting that the public dispute between Moderna and the FDA is uncommon. However, the quick reversal suggests that public pressure may have influenced the FDA’s decision, particularly given the agency’s previous skepticism towards mRNA flu vaccines. STAT News