The Food and Drug Administration (FDA) has approved Moderna’s experimental mRNA influenza vaccine, reversing an earlier decision that blocked the application over concerns about the company’s clinical trial design.
The approval marks a significant turnaround after regulators, under Health and Human Services Secretary Robert F. Kennedy Jr., initially refused to even review Moderna’s submission.
Officials at the time said that the company had failed to compare its vaccine against what officials considered the best available standard of care.
Back in February, FDA vaccine chief Dr. Vinay Prasad concluded that Moderna’s study was not “adequate and well-controlled” because it used GlaxoSmithKline’s Fluarix Quadrivalent vaccine as its comparator rather than a stronger-performing alternative.
FDA Rejects Moderna’s Experimental Flu Vaccine Over Trial Standard Concerns
Moderna CEO Stéphane Bancel insisted regulators had identified “no safety or efficacy concerns” with the vaccine itself, while company president Dr. Stephen Hoge described the FDA’s decision as “all confusing, to say the least.”
Eventually, Dr. Marty Makary, the FDA Commissioner, ordered the agency to review the application after describing the earlier rejection as part of an ongoing regulatory dialogue with manufacturers.
On Wednesday, the FDA granted approval for Moderna’s vaccine, marketed as mFLUSIVA, for adults aged 50 to 64.
The agency also issued accelerated approval for adults 65 and older, allowing the vaccine to be used while additional post-approval data is collected.
Moderna said it expects the vaccine to be available for the 2026-27 flu season.
“Flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America’s seniors,” Bancel said in a statement.
“This approval also reflects the ongoing potential of our mRNA platform to help address important public health challenges through continued scientific innovation.”
Unlike traditional influenza vaccines, which often rely on viruses grown in fertilized chicken eggs, mRNA vaccines can be produced much more quickly.
This will reportedly allow manufacturers to respond faster if new influenza strains emerge.
The approval was based on a clinical trial involving nearly 41,000 adults between the ages of 50 and 64.
According to FDA-reviewed data, recipients of the Moderna vaccine experienced about a 27 percent relative improvement in protection compared with the comparator vaccine.
However, the trial also found higher rates of side effects among Moderna recipients.
Nearly two-thirds reported injection-site pain, while 45 percent experienced fatigue and 38 percent reported headaches, roughly double the rates seen with the comparator vaccine.
Researchers also identified a small number of serious adverse events considered related to the vaccine, including a case of perimyocarditis, inflammation affecting the heart muscle and surrounding tissue.
The approval represents one of the most closely watched vaccine decisions since Kennedy assumed oversight of the nation’s public health agencies.
