FDA Declines Review of Moderna’s Flu Vaccine Application Citing Study Design Issues
Cambridge, Wednesday, 11 February 2026.
The FDA rejected Moderna’s application over comparator selection—a decision management calls inconsistent with prior feedback—triggering a 9% stock drop despite unchanged 2026 financial guidance.
Regulatory Setback Triggers Market Sell-off
On February 10, 2026, Moderna (MRNA) announced that the U.S. Food and Drug Administration (FDA) issued a Refusal-to-File (RTF) letter regarding the company’s application for its investigational seasonal influenza vaccine, mRNA-1010 [1][2]. The regulatory body’s Center for Biologics Evaluation and Research (CBER) declined to review the Biologics License Application (BLA) due to objections regarding the clinical trial’s design, specifically the choice of the comparator vaccine used to benchmark efficacy [1][5]. Following the disclosure, Moderna’s stock declined by 9.04% to trade at $38.20, a downturn that erased approximately $1.63 billion from the company’s market valuation [4].
Procedural Disconnect and Strategic Response
Moderna management has characterized the FDA’s decision as inconsistent with prior regulatory guidance provided throughout the development process [1]. According to the company, CBER reviewed the Phase 3 study protocol in April 2024 and, while suggesting a comparator recommended for older adults, did not object to the use of a standard-dose vaccine at that time [1]. Furthermore, during a pre-submission meeting in August 2025—after the trial had already met its primary endpoints—regulators requested supportive analyses but did not indicate that the filing would be refused [1][4]. Moderna President Stephen Hoge expressed confusion over the sudden shift, noting the company is trying to understand what changed in the regulatory assessment [2].
Global Outlook and Financial Implications
Despite the regulatory halt in the United States, the regulatory process for mRNA-1010 continues to advance in other key markets. The vaccine application has been submitted and accepted for review by agencies in the European Union, Canada, and Australia [1][4]. Moderna anticipates potential approvals in these regions as early as late 2026 or early 2027 [3][4]. This divergence highlights a growing gap between U.S. regulatory standards and international acceptance of Moderna’s clinical data for this specific candidate [4].