The U.S. Food and Drug Administration (FDA) has declined to review a new mRNA-based flu vaccine developed by Moderna, a decision that comes as the nation faces a particularly severe influenza season. The vaccine utilizes the same messenger RNA (mRNA) technology proven effective in COVID-19 vaccines, prompting questions about the FDA’s rationale given the urgency of public health needs.
How mRNA Vaccines Work
mRNA vaccines work by introducing a genetic blueprint – the mRNA – into the body’s cells. These cells then produce harmless viral proteins, triggering an immune response without causing illness. This allows the body to develop protection against future infection. The technology is notable for its speed and adaptability, making it potentially ideal for responding to rapidly evolving viruses like influenza.
FDA’s Reasoning: Study Design Concerns
According to Moderna, the FDA’s rejection isn’t due to safety or efficacy concerns but stems from disagreements over the design of the company’s clinical trials. Vinay Prasad, director of the Center for Biologics Evaluation and Research (CBER), cited issues with the study methodology in a letter to Moderna. The FDA insists the company failed to follow guidance issued in 2024, which required comparing the vaccine’s performance against CDC-recommended flu shots in clinical trials.
Critics Question Transparency
Experts like Angie Rasmussen, a virologist at the University of Saskatchewan, argue the FDA’s decision lacks transparency. “The top U.S. vaccine regulator should base decisions on a systematic review of evidence,” Rasmussen stated, implying the FDA’s process was overly influenced by individual preferences rather than scientific rigor.
Broader Policy Shifts
The FDA’s stance aligns with broader policy changes under Health and Human Services Secretary Robert F. Kennedy, Jr., who has long been critical of mRNA technology and vaccine schedules. This raises concerns about whether political agendas are influencing public health decisions.
Why This Matters: Flu Season Severity
This year’s flu season has been unusually severe, with at least 22 million Americans sickened and over 12,000 deaths reported. The emergence of the K subclade virus has exacerbated the situation, highlighting the need for rapid vaccine development. mRNA technology could allow for quicker updates to flu shots to match circulating strains, but the FDA’s decision delays that possibility.
“If we had recognized [subclade K] was going to be driving things, and were using mRNA vaccines instead of conventional platforms, we could have had an updated shot ready for flu season,” says Rasmussen.
The FDA’s decision raises questions about whether bureaucratic hurdles are hindering access to potentially life-saving technology during a critical public health crisis.
