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In a recent development, the U.S. Food and Drug Administration (FDA) has turned down Moderna’s bid for approval of a new flu vaccine developed with groundbreaking mRNA technology, as announced by the company on Tuesday.
This decision highlights the FDA’s increased vigilance over vaccines, particularly those employing mRNA technology, a point of contention for Health Secretary Robert F. Kennedy Jr., who has been vocal in his skepticism both before and during his tenure as the nation’s leading health official.
Moderna’s application was met with a “refusal-to-file” letter from the FDA, which took issue with the methodology of a substantial clinical trial involving 40,000 participants. The trial had aimed to compare the efficacy of Moderna’s new vaccine against a traditionally used flu shot. Findings suggested that the new vaccine offered slightly better protection for adults aged 50 and older.
Dr. Vinay Prasad, director of the FDA’s vaccine division, stated that the trial did not constitute an “adequate and well-controlled” study. The critique centered on the fact that the comparison did not involve what the FDA considered the “best-available standard of care” in the U.S. at the time. Dr. Prasad’s letter referenced guidance provided to Moderna in 2024 during the Biden administration, which suggested using a different standard for participants aged 65 and older—a suggestion Moderna opted not to fully incorporate.
Moderna contends that the feedback indicated it was permissible to use the standard-dose flu shot they selected for the trial. However, the FDA had shown a preference for another brand, specifically recommended for seniors. Despite this, Moderna maintains that the FDA had initially agreed to the study’s original design.
The company said it also had shared with FDA additional data from a separate trial comparing the new vaccine against a licensed high-dose shot used for seniors.
The FDA “did not identify any safety or efficacy concerns with our product” and “does not further our shared goal of enhancing America’s leadership in developing innovative medicines,” Moderna CEO Stephane Bancel said in a statement.
It’s rare that FDA refuses to file an application, particularly for a new vaccine, which requires companies and FDA staff to engage in months or years of discussions.
Moderna has requested an urgent meeting with FDA, and noted that it has applied for the vaccine’s approval in Europe, Canada and Australia.
In the last year, FDA officials working under Kennedy have rolled back recommendations around COVID-19 shots, added extra warnings to the two leading COVID vaccines — which are made with mRNA technology — and removed critics of the administration’s approach from an FDA advisory panel.
Kennedy announced last year that his department would cancel more than $500 million in contracts and funding for the development of vaccines using mRNA.
FDA for decades has allowed vaccine makers to quickly update their annual flu shots to target the latest strains by showing that they trigger an immune response in patients. That’s a far more efficient approach than running long-term studies tracking whether patients get the flu and how they fare. In an internal memo last year, Prasad wrote that the streamlined method would no longer be permitted – leading more than a dozen former FDA commissioners to pen an editorial condemning the statements.