The Food and Drug Administration rejected Moderna’s application for its mRNA-based flu vaccine, the drugmaker said Tuesday.
The move is the latest sign that the FDA, under Health Secretary Robert F. Kennedy Jr., is slow-walking vaccine approvals and taking a harder line on shots that use messenger RNA technology.
Moderna’s vaccine uses the same mRNA technology as its Covid shot.
In a release Tuesday, Moderna said the FDA did not identify any safety or efficacy concerns with the vaccine. Instead, it said the FDA took issue with the “comparator” in its clinical trial — the vaccine the company used as a benchmark to evaluate its own shot.
The FDA said the use of the standard flu shot as a comparator “does not reflect the best-available standard of care.” The standard flu shot is FDA-approved.
However, Moderna said that the agency’s stated reason is “inconsistent” with what regulators had told the company in 2024 and 2025.
“It should not be controversial to conduct a comprehensive review of a flu vaccine submission that uses an FDA-approved vaccine as a comparator in a study that was discussed and agreed on with CBER prior to starting,” Moderna CEO Stéphane Bancel said in the release, referring to the FDA’s Centers for Biologics Evaluation and Research, which reviews and approves vaccines, as well as other treatments such as gene therapies.
Moderna said last year that its mRNA flu shot was 26.6% more effective than the standard flu shot, based on a Phase 3 clinical trial.
In an emailed statement, Andrew Nixon, a spokesperson for the Department of Health and Human Services, which oversees the FDA, said: “The FDA generally does not comment on regulatory communications to individual sponsors.”
Last year, Kennedy ordered that all new vaccines go through placebo-controlled clinical trials.
When vaccines are already available for a disease, it's considered unethical to give clinical trial participants a placebo, rather than compare the new vaccine to the existing one. Giving a placebo would leave people who would be otherwise protected vulnerable to infection.
Last May, Moderna withdrew its application seeking approval for its combination flu and Covid mRNA shot after the FDA asked for more data.
Kennedy, an anti-vaccine activist, has downplayed the benefits of vaccines and has singled out vaccines made with mRNA as particularly dangerous, calling the mRNA Covid vaccine “the deadliest vaccine ever made.”
Numerous studies have shown the mRNA vaccines are safe and effective. A 2023 analysis in JAMA Pediatrics reviewed 17 studies covering more than 10 million children ages 5 to 11 who got Pfizer’s or Moderna’s Covid vaccines. Vaccinated kids had a lower risk of infection and hospitalization compared to those who weren’t vaccinated.
In August, the Department of Health and Human Services canceled nearly $500 million in funding into mRNA vaccine research.
Several states have introduced legislation to ban mRNA vaccines.
Regulators in the European Union, Canada and Australia have accepted Moderna's mRNA flu vaccine application, the company said.
