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FDA sets new COVID booster guidelines requiring trials for approvals for healthy adults
By Michael Erman - 5/20/2025
By Michael Erman
NEW YORK (Reuters) -The U.S. Food and Drug Administration plans to require new clinical trials for approval of annual COVID-19 boosters for healthy Americans under 65, effectively limiting their availability later this year to older adults and those at risk of developing severe illness, FDA leaders said on Tuesday.
FDA Commissioner Marty Makary and top U.S. vaccines regulator Vinay Prasad wrote in the New England Journal of Medicine that the benefit of repeated annual shots for healthy adults was uncertain after several years of the virus circulating and vaccines being available.
They also said that the U.S. was an outlier among high-income nations in recommending yearly shots for healthy adults.
Investors reacted favorably to the news and shares of COVID vaccine makers rose. In late morning trading, shares of Moderna were up 11.2% at $29.24, Pfizer rose 2.2% to $23.51 and Novavax shares were up 2.2% at $7.91.
Makary and Prasad said they expect the FDA will be able to approve the boosters for adults over the age of 65 years based on data from tests that measure immune response in patients.
The shots would also be available for everyone over the age of six months with one or more risk factors that put them at high risk for severe COVID-19 outcomes, they said.
But for healthy people between the ages of six months and 64 years, the FDA expects it would need randomized, controlled trials for drugmakers to get approval for annual shots.
Vaccine makers have argued that because COVID vaccines have been changed annually to match the circulating strain of the virus, new placebo-controlled trials could delay availability of the shots until after their usefulness has passed.
But Prasad and Makary say the studies are needed to provide evidence that annual shots for healthy younger Americans are evidence-based.
"We simply don’t know whether a healthy 52-year-old woman with a normal BMI who has had Covid-19 three times and has received six previous doses of a Covid-19 vaccine will benefit from the seventh dose," Prasad and Makary wrote. "This policy will compel much-needed evidence generation."
There are currently three approved vaccines for COVID-19 in the U.S.: messenger RNA-based shots made by Moderna Inc and by Pfizer and Germany's BioNTech, and a protein-based vaccine made by Novavax Inc. The companies did not immediately respond to requests for comment.
"This is quite reasonable. The really high risk people - people over 65, people with chronic medical conditions - can still get the vaccine," said Dr. David Boulware, an infectious disease specialist at the University of Minnesota.
Boulware said he believed it was unlikely that vaccine makers will conduct the clinical trials to receive the broader approval, saying it would require large enrollment and could cost "hundreds of millions of dollars."
U.S. Health and Human Services Secretary Robert F. Kennedy Jr. is a vaccine skeptic, who has long sown doubts about the safety and efficacy of the shots.
Makary and Prasad - both new to the FDA this year - have been critical in the past of the approval process and the evidence supporting the necessity of annual COVID-19 shots for many Americans.
Still, they acknowledged that the 2020 development of the shots were a major scientific, medical, and regulatory accomplishment. They also called the measles-mumps-rubella vaccine a vital immunization and said it had been "clearly established as safe and highly effective."
COVID vaccines are significant products for drugmakers, even as uptake has fallen post-pandemic. In 2024, U.S. sales of COVID boosters - sold primarily by Pfizer and Moderna - topped $3.5 billion.
When Novavax's shot was approved last week, the FDA limited its use to older adults and people over the age of 12 with conditions that put them at risk of severe illness.
According to the U.S. Centers for Disease Control and Prevention, a wide list of conditions constitutes an additional risk including obesity, diabetes and heart disease, as well as behaviors like physical inactivity and substance abuse.
Makary and Prasad said that estimates suggest that some 100 million to 200 million Americans would have access to the annual shots under these new terms.
The FDA's vaccine advisory committee is scheduled to meet later this week to discuss which variant of the coronavirus vaccine makers should target ahead of the COVID season this year.
(Reporting by Michael Erman, editing by Deepa Babington)