FDA denies review of Moderna’s mRNA flu vaccine application

FDA Declines Review of Moderna’s mRNA Influenza Vaccine

The U.S. Food and Drug Administration has decided to reject Moderna’s application for a new influenza vaccine that utilizes mRNA technology. This announcement, made by the company on Tuesday, may postpone the rollout of a vaccine aimed at enhancing protection for older adults.

Moderna explained that it received a “rejection of application” (RTF) letter from the FDA’s Center for Biologics Evaluation and Research (CBER). The letter pointed out that the company had not provided “appropriate and well-controlled” studies involving comparator groups and noted that the application “does not reflect the best available standards of care.”

In response, Moderna’s CEO, Stéphane Bancel, stated that the FDA’s choice “does not identify any concerns regarding the safety or efficacy of our products.” He expressed disappointment, saying it does not contribute to the collective aim of advancing America’s leadership in innovative medicine.

Bancel added, “We will thoroughly review influenza vaccine applications using FDA-approved vaccines as comparators in studies that were previously discussed with CBER.” He expressed eagerness to collaborate with CBER to clarify the next steps so that older Americans and those with underlying health conditions can access innovative American-made solutions.

The FDA’s decision comes at a time when vaccine approvals are facing increased scrutiny under Secretary of Health Robert F. Kennedy Jr. His administration has raised questions about mRNA vaccines, even reversing some COVID-19 vaccination guidelines in the past year.

Poor decisions continue as Kennedy has appointed new members to the federal vaccine advisory committee and has also terminated a significant $500 million mRNA vaccine contract. Last fall, the FDA allowed COVID-19 vaccines to be administered only to high-risk groups. In May, Kennedy announced plans to remove the vaccine from the CDC’s standard immunization schedule for healthy children and pregnant women.

Moderna’s application was particularly criticized for its selection of a comparator, an approved standard-dose seasonal flu vaccine, which the FDA deemed inferior in reflecting the “best available standard of care.”

The company argued that this decision contradicts prior communications from the FDA. For instance, guidance from 2024 suggested higher doses for participants aged 65 and above while allowing standard-dose comparators.

Moderna highlighted that the FDA had not raised any significant objections regarding the Phase 3 study following the submission of the protocol in April 2024, nor before the trial began in September 2024.

In August 2025, following the conclusion of the Phase 3 efficacy study, Moderna met with CBER, where the agency asked for additional analysis on the comparator. This request indicated the data would be a “significant issue during BLA review.” Moderna claimed it complied with this request, asserting that CBER had not indicated any refusal to review the file prior to submission.

The company has asked for a Type A meeting with CBER to gain insight into the reasoning behind the RTF letter and noted that regulatory evaluations are still ongoing in the EU, Canada, and Australia.