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U.S. regulators will no longer approve COVID booster shots for healthy adults and children without new studies, adding a costly requirement for drugmakers, though they will still be available for millions of high-risk Americans.

Food and Drug Administration Commissioner Marty Makary and Vinay Prasad, who leads the agency's vaccine division, outlined the approach the agency intends to take with updated versions of the immunizations in an article published Tuesday in the New England Journal of Medicine.

The agency's willingness to continue making the shots available to high-risk people with a wide range of health conditions was a relief to the industry, which feared a wave of restrictions from President Donald Trump's political appointees who questioned the vaccines. Investors were buoyed as the new policy doesn't require the costly trials for older adults, who are more likely to get vaccinated.

Moderna Inc.'s shares rose 6.5% as of 12:23 p.m. in New York. Pfizer Inc. gained 1.6% and Novavax Inc. was up 3%.

The new FDA guidance "may be a silver lining" for COVID vaccine makers because it could increase the use of the shots given how many people have other health conditions, Bloomberg Intelligence analyst Sam Fazeli said. Vaccination rates have been in decline, with just 23% of U.S. adults getting the latest booster, according to the Centers for Disease Control and Prevention.

Required research

Typically, with seasonal vaccines like the flu, drugmakers are able to introduce new formulas designed to match the mutating virus based on simple tests that show they generate a strong immune response. These faster reviews follow initial approvals based on rigorous trials proving the shots are safe and reduce the risk of infection and death.

Going forward, the FDA expects drugmakers to do full studies before it approves updated immunizations each season for those six months to 64 years old without health issues that put them at high risk, Makary and Prasad wrote. Shots for the elderly and those with health risks, a group they say encompasses between 100 million and 200 million Americans, will be cleared using the current approach that doesn't require extensive studies.

The rigorous trials, which involve testing against a placebo, are typically considered unethical when a vaccine already exists because it involves withholding proven protection and potentially exposing people to preventable illness. Manufacturers have also worried that it may be difficult to do another study in time for the fall immunization season.

The range of high-risk conditions that will allow for vaccine use without additional studies is broad, including people who are obese and have mental health conditions like depression, the FDA officials wrote.

It's unclear whether drug companies would do the trials to get broader approval. Moderna, Pfizer, and Novavax, which make COVID vaccines, didn't immediately respond to requests for comment.

New direction

Changes in who gets COVID vaccinations have been looming for some time. While the shots are currently recommended for everyone aged six months and older, a group of Centers for Disease Control and Prevention advisers is debating whether they should only be offered to high-risk children and adults. Such a move would make it even less attractive for companies to do additional studies.

The FDA is changing its approach in part because the benefits of repeat COVID shots—particularly among low-risk people who may have already gotten boosters or been infected by the virus multiple times—are uncertain, Makary and Prasad wrote.

The FDA's new policy "represents a balance of regulatory flexibility and a commitment to gold-standard science, " they said. "The FDA will approve vaccines for high-risk persons, and at the same time, demand robust, gold-standard data on persons at low risk."

The FDA has already started to limit who can get COVID shots. Last week, the agency gave full approval to a COVID vaccine from Novavax, but for a narrower group that includes adults 65 and older and those ages 12-to-64 who have at least one underlying condition. The agency also required the company to conduct additional safety trials, including evaluating the risk of myocarditis, or inflammation of the heart muscle.

Moderna, meanwhile, is currently awaiting an FDA decision on a new version of its COVID vaccine. The article didn't address the company's situation

More information: Vinay Prasad et al, An Evidence-Based Approach to Covid-19 Vaccination, New England Journal of Medicine (2025). DOI: 10.1056/NEJMsb2506929  Journal information: New England Journal of Medicine

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