The United States Food and Drug Administration (FDA) has refused to review Moderna’s application for approval of a flu vaccine, raising concerns amid a recent rollback of longstanding vaccine guidelines.
In a letter to Moderna, the FDA pushed back on the Massachusetts-based biotech company’s rationale comparing its mRNA -1010, a product already on the market, to a standard dose for the seasonal flu, the company revealed on Tuesday evening.
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The federal agency cited that as the reason it declined to review the application, which claimed there was a lack of “adequate and well-controlled” data. Moderna said the letter claimed that the FDA thought the biotech giant’s flu vaccine “does not reflect the best-available standard of care”.
The company has pushed back on the allegation, and CEO Stephane Bancel said the letter “did not identify any safety or efficacy concerns with our product”.
Experts say the lack of guidance isn’t helpful.
“If there are things that need scrutiny, a review process can address them. At the end of the review, they can identify the issues that need to be corrected. That gives the company an opportunity to make changes and adapt. When that guidance isn’t provided, it makes it very difficult for someone submitting materials to know how to proceed,” Bruce Y Lee, a professor of health policy and management at the CUNY Graduate School of Public Health and Health Policy, told Al Jazeera.
Last year, Moderna said that its mRNA-1010 vaccine is 26.6 percent more effective than an approved annual flu vaccine from GlaxoSmithKline.
“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 [Center for Biologics Evaluation and Research] prior to starting,” Bancel said.
In terms of the next steps for Moderna, William Soliman, CEO of the Accreditation Council for Medical Affairs, a healthcare trade group, said typically a company would need to go back and continue study in a case like the one facing Moderna.
“They [Moderna] would have to provide additional analysis or alter the study design and resubmit it for review. That’s typically how it works: they go back, address whatever the FDA is requesting, and then resubmit,” Soliman told Al Jazeera.
In 2025, 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 influenza 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.
Political undertones
The FDA action comes amid concerns over transparency within the organisation, raising questions among experts if the decision-making process to reject the application was merit-based or politically motivated.
“A big question is whether this is part of some type of political agenda. Many of the policies and decisions we’ve seen have been rolling back vaccine policies long supported by the science, again without clear explanation why, so the concern is that this is part of a larger trend,” Lee said.
According to the healthcare trade publication Stat News, career scientists were ready to review the application, including the head of the US agency’s vaccine office, David Kaslow, but were overridden by FDA commissioner Vinay Prasad, which the agency has disputed.
Al Jazeera was unable to independently verify the claims. The Department of Health and Human Services (HHS) did not respond to Al Jazeera’s request for comment.
In August, HHS, the federal agency that the FDA operates under, announced it would scale down mRNA vaccine development.
Robert F Kennedy Jr, who leads HHS, is a known vaccine sceptic. Since he was appointed health secretary, there has been a rollback in vaccine guidance, which included recommendations for routine vaccines on six infectious diseases, including influenza, and new guidance on childhood immunisation.
The rates of diseases otherwise preventable by vaccines have skyrocketed. In the US, there were more than 2,200 measles cases in 2025, the highest in nearly three decades, and so far this year, there have been more than 730 reported cases.
Wall Street strain
Moderna, which rose to prominence with its COVID-19 vaccine, has seen a sharp decline on Wall Street over the past year as vaccine sales dropped alongside falling case numbers. In its most recent earnings report, released in November, the company posted a $200m quarterly loss, with profits down $13m from a year earlier.
The company has struggled to regain its footing amid the slump in sales.
The FDA’s decision “throws a wrench into the company’s reliance on seasonal vaccines to reach its 2028 cash break-even goal,” Citi Research analyst Geoff Meacham told the Reuters news agency.
Moderna’s stock has fallen 29 percent in 2025 alone and is down more than 90 percent from its 2021 peak.
Moderna’s stock tumbled in early trading but has begun to rebound. It is still far below the market open and was down 4.7 percent in midday trading on Wednesday, following news that the FDA refused to review its application.
