The Food and Drug Administration has refused to review Moderna’s application for its seasonal flu vaccine, the company announced Tuesday, Feb. 10, marking the latest setback for the development of mRNA-based vaccines.
In a news release, Moderna said it received a “refusal-to-file” letter from the FDA that took issue with the company’s decision to compare its new vaccine to a licensed standard-dose seasonal influenza shot. The company noted that the FDA did not identify any specific safety or efficacy concerns with the vaccine.
The letter from Dr. Vinay Prasad, director of the FDA’s Center for Biologics Evaluation and Research, specifically cited that the application did not contain an “adequate and well-controlled” trial because the control arm “does not reflect the best-available standard of care.”
Moderna said the FDA’s rejection was inconsistent with feedback the agency provided in 2024 and 2025. The company added that it has requested a meeting with the regulator to “understand the path forward.”
“This decision by CBER (Center for Biologics Evaluation and Research), which did not identify any safety or efficacy concerns with our product, does not further our shared goal of enhancing America’s leadership in developing innovative medicines,” Moderna CEO Stéphane Bancel said in a statement.
“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,” Bancel added.
The company used Fluarix as its standard-dose comparator in an over 40,000-person clinical trial for the new mRNA flu shot, called mRNA-1010. Moderna said last year the mRNA-1010 vaccine was 26.6% more effective than an FDA-approved annual flu shot.
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Moderna previously said it won’t invest in new late-stage vaccine trials
During the World Economic Forum in Davos, Switzerland, in January, Bancel said the company does not plan to invest in new late-stage vaccine trials because of growing opposition to immunizations from U.S. officials.
“You cannot make a return on investment if you don’t have access to the U.S. market,” Bancel told Bloomberg TV, adding that regulatory delays and a lack of support from officials make the market size “much smaller.”
Last year, Moderna withdrew its application seeking approval for its flu and COVID combination vaccine to wait for efficacy data from a late-stage trial of its flu vaccine. The vaccine is currently under review in the European Union, Canada, and Australia, with the company expecting potential approvals to come in late 2026 or early 2027.
Decision comes amid government’s scrutiny of vaccines
The move comes just over a month after federal regulators overhauled their longstanding guidance on childhood immunization and rolled back recommendations for routine vaccination against six infectious diseases, including the flu.
In August 2025, the Department of Health and Human Services said it would wind down mRNA vaccine development activities under its biomedical research unit. The unit, Biomedical Advanced Research and Development Authority, helped companies develop medical supplies to address public health threats, and had provided billions of dollars for developing vaccines during the COVID-19 pandemic.
Health Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic who has been making sweeping changes to vaccines, food, and medicine policies, said the decision will impact 22 projects worth nearly $500 million at the Biomedical Advanced Research and Development Authority.
Major medical organizations and health experts have criticized Kennedy’s policies, including Jerome Adams, the U.S. Surgeon General under President Donald Trump’s first term. Following the Department of Health and Human Services’ announcement in August, Adams said mRNA vaccine cuts were “going to cost lives.”
“mRNA technology has uses that go far beyond vaccines … and the vaccine they helped develop in record time is credited with saving millions,” Adams said in a post on X.
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How do mRNA vaccines work?
Messenger RNA, or mRNA, is a code that tells the body’s cells to produce just a piece of the virus, the protein on the surface. The code is protected by lipid coating, like a fat bubble.
Once injected into the body, the vaccine releases the mRNA to program the cell to produce spike proteins like those on the surface of SARS-CoV-2, the COVID-19 virus. The human immune system recognizes vaccine-created spike proteins as invaders and creates antibodies to block future attacks from the virus.
Messenger RNA vaccines contain only a fraction of the virus, so unlike some vaccines, they can’t give people the disease they’re trying to prevent or trigger allergies to eggs or other traditional vaccine ingredients.
Contributing: Melina Khan, Adrianna Rodriguez, and Eduardo Cuevas; USA TODAY; Reuters
This article originally appeared on USA TODAY: FDA declines to review Moderna flu vaccine
