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Seattle vaccine experts were surprised and confused by the country's apparent new direction around updated COVID-19 shots, which top officials at the Food and Drug Administration revealed Tuesday and appears to restrict availability to older adults and people at higher risk for severe disease.
Immunization researchers here and nationwide spent the day trying to sort through the latest framework for approving and licensing updated COVID vaccines in the U.S., a change that confirms what FDA leaders had been hinting at for weeks. While local vaccine experts say the shift comes from a reasonable place — to gather better evidence around the long-term benefits of boosters — they pushed back against certain FDA claims, and questioned whether this strategy was the best way forward.
"There are all sorts of ways to handle this problem," said Dr. Helen Chu, a professor of allergy and infectious diseases at University of Washington's School of Medicine. "I just don't think this is the solution."
According to the framework, published in the New England Journal of Medicine, new versions of the COVID vaccine — which have been developed annually to take into account emerging variants — will still be available for adults over 65 and younger people at higher risk for serious illness. But for everyone else, including children, the FDA will push manufacturers to conduct large clinical trials before shots are greenlit, the guidance says.
Under the previous approval process, the FDA licensed updated COVID shots for everyone 6 months and older every year.
This new framework aims to ensure timely approval to a broad population while "(balancing) the need for evidence," FDA Commissioner Marty Makary and the agency's vaccine chief, Dr. Vinay Prasad, wrote Tuesday.
Peter Gilbert, a biostatistician who works on vaccine clinical trials at Fred Hutchinson Cancer Center, said this change will probably lead to delays in approval that'll likely translate to more severe COVID cases.
Makary and Prasad estimate about 100 million to 200 million Americans would still be eligible to get updated shots, including people with asthma, cancer, heart conditions, obesity and mental health conditions, like depression. Updated vaccines would also remain available for pregnant people and current and former smokers, the policy says.
But the 1,000-word plan leaves a range of pressing questions unanswered about the rest of the population, prompting concerns among even some of the nation's top vaccine experts. What would these clinical trials look like, and how long would they take? What kind of impact would this change have on instances of long COVID?
COVID continues to pose serious health risks in Washington, including hospitalizations, long COVID and preventable deaths, and vaccination is still one of the most effective tools in protecting against the virus, the state Department of Health said in a Tuesday statement.
"At this time, we are not making any changes to our programs or recommendations and will continue to monitor federal guidance as it evolves," the statement said.
There is some truth to the claims informing the changed federal policy, experts say: There isn't great up-to-date data that shows younger, healthy adults should get an updated COVID shot every year, Chu said. But it's unusual for the FDA, which generally addresses safety issues, to offer recommendations around vaccine effectiveness, she said.
"It's outside the scope of the FDA to be making these types of recommendations for age groups and risk groups for a vaccine," she said.
That responsibility usually sits squarely with the Centers for Disease Control and Prevention, said Chu, who since 2024 has been a member of the CDC's Advisory Committee on Immunization Practices — a group of up to 19 independent medical and public health experts that are tasked with analyzing data and making vaccine recommendations.
But Makary and Prasad dove into the topic this week, criticizing the country's "one-size-fits-all" approval model and arguing the U.S. approach to recommending COVID vaccines for everyone 6 months and older is outdated, since many people have developed some immunity to SARS-CoV-2 through vaccination, infection or both.
Under the new framework, the FDA will encourage vaccine makers to conduct randomized, placebo-controlled trials of healthy adults before approving any updated COVID shots — a method that could collect better data in theory, but one Chu said "makes very little sense" in practice.
Because there's already an approved COVID vaccine in the U.S., it would be unethical to withhold that protection by conducting a trial with a placebo group, she said. Because COVID can cause severe disease, "you can't do a (randomized, controlled trial) with a placebo arm for a vaccine that's licensed and effective," she added.
The change also assumes particular biomarkers, known as neutralizing antibody titers, are no longer an effective way to measure immune response in young, healthy people. Based on that assumption, the FDA says, we shouldn't rely on that test when developing new COVID vaccines for people not at high risk, and should instead run each version through lengthy clinical trials.
However, there isn't evidence that assumption is accurate, said Gilbert of Fred Hutch.
"We know that the neutralizing antibody titer is good enough, that by not being able to rely on it, it will probably slow down the process," Gilbert said. "That means new, or better, vaccines will take longer to be identified and get deployed."
That's a key reason researchers work so hard to prove biomarkers are reliable enough to support the basis of licensure, added Holly Janes, who also works at Fred Hutch as a biostatistician and helped develop early COVID vaccine trials.
Depending on the structure of the trial, it could take more than a year to recruit participants, follow them for months, collect data and analyze results, she said.
"If this needed to be done for each and every vaccine that incorporates a new variant that might emerge, it's a little unclear as to how and whether that trial would be feasible to conduct on the timescale that would be needed," Janes said.
In addition, pharmaceutical companies could always decide they aren't able or don't want to put the work into conducting these expensive trials — in which case, annual, updated COVID shots would not be licensed for those under 65 and without underlying health conditions.
While the policy change sparked concern about who might be able to get a COVID booster this fall, Makary and Prasad pointed to the country's low rates of updated vaccination in recent years. According to the CDC, less than 25% of Americans get annual COVID shots, ranging from under 10% in children under 12, to about 50% of adults over 75, they wrote.
Booster rates are also low in Washington state, where about 19% of residents 6 months and older have received an updated shot this season, according to data from the Department of Health. About 70% of Washingtonians received their full primary series, state data show.
About 82% of King County residents have been immunized with their primary series, though just 26.5% of residents received an updated shot this season.
The CDC advisory group Chu serves on is scheduled to meet in June to vote on updated recommendations around COVID vaccines. But this new policy from the FDA does limit what the group is able to recommend, since they can really only back a licensed vaccine, Chu said.
"This was a very fast and shocking decision," she said. "This is basically taking COVID and moving us back to things we knew didn't work."
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