On May 20, the federal government announced a major shift in how it plans to review and recommend COVID-19 vaccines for Americans. Among the changes: when manufacturers want to update the vaccine each year to target the latest variants, they will be required to conduct additional studies to show the effectiveness of the vaccine in people who are not at high risk of severe COVID-19.
Since 2023, federal health officials have recommended an annual COVID-19 shot for most people, and vaccine makers have not needed to conduct additional tests on each year’s updated vaccine. It’s similar to the way the annual flu shot is updated to target the newest influenza strains, without new studies to re-confirm the effectiveness and safety of the vaccine.
Here’s how COVID-19 vaccine guidance is changing in the U.S.
For people at high risk of severe COVID-19
The process of reviewing and recommending yearly updates to the COVID-19 vaccine would remain essentially the same for anyone at high risk of developing severe COVID-19, which includes older people and anyone with compromised immune systems or a broad range of risk factors. “If you’re older than 65 or you are at high risk of COVID-19, we’re going to use the immunologic endpoints we’ve been using to grant approval,” said Dr. Vinay Prasad, head of the U.S. Food and Drug Administration’s Center for Biologics Evaluation and Research (the group that oversees approvals for vaccines and biologic treatments), during a May 20 briefing. “This is a tremendously broad category; this effectively means 100 million to 200 million Americans, those with the most favorable benefit-to-harm balance, will be covered by these approvals.”
That means that additional studies of updated vaccines involving these groups will not be required. Vaccine makers will continue, however, to conduct studies to ensure the shots are safe after they are available.
In a medical journal commentary describing the changes, Prasad and FDA commissioner Dr. Martin Makary said that such a study “does not preclude the conduct of additional randomized studies, particularly studies in pediatric populations.” Prasad said during the briefing that another scenario that might require additional studies on updated vaccines would be if the virus mutates and changes in a significant way. These would be conducted on an as-needed basis, but not necessarily yearly.
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The “high-risk” category is broad. It includes conditions like asthma, diabetes, and depression—but also physical inactivity, which can be a more subjective health characteristic and applies to most U.S. adults. It’s not clear how much documentation, if any, people will have to provide in order to be eligible to receive a COVID-19 vaccine if they want to get immunized. As they did when a different policy restricted the original COVID-19 vaccines to high-risk groups, doctors and pharmacists will likely make individual and varied decisions about whether people who have these risk factors qualify—and may err on the side of vaccinating people if they want the shot.
For people who are not at high risk of severe COVID-19
Prasad said the process for approving annual COVID-19 vaccines for people not at high risk will change. The FDA is now telling vaccine makers to conduct additional studies to show that their vaccines provide benefit—in outcomes including lower rates of symptoms, hospitalizations, and deaths from COVID-19—compared to people receiving placebo.
The six-month trials would follow people ages 50 to 64 years. (Those results would then be generalized to healthy people as young as six months.) But because some people don’t develop symptoms, and others may only experience mild ones—especially after repeat infections—it could take a very large study to get enough cases to give the results enough statistical power to make them meaningful. That would add to the cost of the vaccines for manufacturers, which could then get passed down to consumers.
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“We are evaluating the details shared today and discussions with the FDA are ongoing,” said Pfizer in a statement. “We stand by the science behind the Pfizer-BioNTech COVID-19 vaccine and continue to believe that broad vaccination programs are an essential tool for helping to prevent COVID-19 associated hospitalizations and severe disease, including death. The Pfizer-BioNTech COVID-19 vaccines have been administered to over a billion individuals, including adults, adolescents and children, generating robust data demonstrating a favorable safety profile.”
Moderna responded to the new policies by saying “we appreciate the FDA’s clear guidance and remain committed to working with the Agency to provide the data they need to ensure access for Americans.”
As of April 2025, only about 23% of U.S. adults got the latest COVID-19 shot—which Prasad cites as evidence that the public is unconvinced that the shot adequately protects against disease. He also said that many Americans have now had multiple COVID-19 infections, which provides immunity for some period of time, and that the effectiveness of the vaccines in providing protection in such a population isn’t clear.
Public-health experts acknowledge that specific studies on these populations have not been conducted, but point to generally declining rates of hospitalizations and deaths from COVID-19 as an indicator that immunity to the virus, provided in part by vaccinations, is likely playing a role.
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