FDA Reverses Decision, Agrees to Review Moderna's mRNA Flu Vaccine
The FDA has agreed to review Moderna's mRNA influenza vaccine application after initially rejecting it, following modifications by the company. A decision is expected by August 5, 2026.
The U.S. Food and Drug Administration has agreed to review Moderna's influenza vaccine, reversing an earlier decision to reject the application after the company made modifications. The reversal announced Wednesday comes just a week after the FDA's surprise decision to not review the company's experimental flu vaccine application.
The FDA has accepted Moderna's revised approach, seeking full approval for the shot for adults aged between 50 and 64, and accelerated approval for those aged 65 and above, the company said, adding that it will also conduct a post-marketing study in older adults. The regulator is expected to make a decision on the candidate by Aug. 5.
In September 2024, Moderna launched its vaccine trial with 40,700 subjects, half of whom received the mRNA flu vaccine and the other half standard-dose vaccine. The mRNA vaccine was 27% more effective at preventing symptomatic cases of flu and 49% more effective against hospitalization than the standard-dose flu vaccine. Moderna had also performed an additional study in 2,200 people over 65 showing that the mRNA flu vaccine induced higher levels of protective antibodies than the high-dose flu vaccine.
On February 3, 2026, despite a previous written understanding, the FDA refused to review Moderna's application for licensure of its mRNA influenza vaccine. The decision was made by Vinay Prasad, who now heads the FDA's Center for Evaluation and Research (CBER). Moderna wrote that the failure to review the application was "inconsistent with previous written communications from CBER to Moderna."
The regulator had defended its initial decision, saying the company should have given a higher-strength vaccine to older patients in the control arm of its trial. In April 2024, the FDA had pointed out that for people over 65, Moderna should compare its mRNA flu vaccine to high-dose, not standard dose, flu vaccine, as recommended by the CDC. However, if the company still planned to compare the mRNA vaccine with standard dose flu vaccine for those over 65, the CDC might choose not to recommend it for that age group. Because the clinical trial of the mRNA flu vaccine was performed in Europe, where high-dose influenza vaccine wasn't readily available, the company moved forward recognizing that it might not get a CDC recommendation for older subjects, but that the FDA would still review the company's submission. This was a written understanding.
The mRNA technology used in Moderna's and most other COVID-19 shots, credited with saving millions of lives, comes with a shift in health policy under U.S. Health Secretary Robert F. Kennedy Jr., a longtime anti-vaccine activist who has been particularly critical of mRNA vaccines.
"Pending FDA approval, we look forward to making our flu vaccine available later this year so that America's seniors have access to a new option to protect themselves against flu," the CEO stated.
Health Canada said it accepted Moderna's mRNA influenza vaccine for review on Jan. 28, 2026, "with a decision anticipated within the standard review timeline of 300 days" after acceptance. Moderna said it has also applied for the vaccine's approval in Europe and Australia.