By MATTHEW PERRONE and LAURAN NEERGAARD, Associated Press

WASHINGTON (AP) — Government advisers are meeting Thursday to decide if COVID-19 vaccines need updating to improve protection this fall and winter — even as a new Trump administration policy has thrown into question who may be eligible for a shot.

The Food and Drug Administration’s outside experts have met regularly since the launch of the first COVID-19 vaccines to discuss tweaking their recipes to stay ahead of the virus. Thursday’s meeting is the group’s first since President Donald Trump took office.

But it comes just two days after FDA leaders upended the prior U.S. policy of recommending annual COVID-19 boosters for all Americans ages 6 months and older.

Instead, the FDA said routine approval of COVID-19 boosters will be limited to seniors and to younger people who are at high risk of severe infection. Manufacturers will need to do new studies to show whether seasonal shots still benefit healthy people younger than 65.

That raises big implications for next fall’s vaccination campaign, with uncertainty over whether healthy people still could get a vaccine even if it’s not recommended for them — or whether insurers will keep paying for the shots for everyone. Nor is it clear what the policy means for babies who have never been vaccinated.

“This is a mess,” said Michael Osterholm, a University of Minnesota infectious disease expert. “The one thing we don’t want to do is put a barrier in place that prevents parents from getting their children vaccinated if they want to.”

FDA’s independent advisers may raise those issues Thursday, but the changes are not the focus of the meeting, which was scheduled before FDA’s announcement.

Instead, the panel is set to recommend whether the virus has mutated enough to warrant strain updates for shots from Pfizer, Moderna and Novavax.

“We are asking for guidance to help the FDA decide what strain to select for COVID-19 vaccines going forward,” FDA vaccine chief Dr. Vinay Prasad said in comments opening the meeting. Prasad added that the agency wants “to give people a little more time to digest,” the new policy on vaccines and is open to feedback.

Last fall’s recipe was tailored to omicron descendants on the JN.1 branch of the virus family tree. Novavax brewed shots targeting the parent JN.1 variant while Pfizer and Moderna opted for a subtype called KP.2.

That JN.1 family still dominates, although it continues to evolve. The question is whether last fall’s shots still offer enough cross-protection or if manufacturers instead should match today’s most common subtype, called LP.8.1.

The World Health Organization recently said last year’s version was OK but that vaccine makers could choose an update. The European Medicines Agency instead recommended targeting the newest subtype.

FDA officials didn’t express a preference in documents posted online ahead of Thursday’s meeting. suggested earlier in the week that the government should move away from yearly updates.

“Instead of having a COVID-19 strategy that’s year-to-year where we change things every single year, why don’t we let the science tell us when to change?” Prasad said.

Debating that science is what the FDA’s vaccine advisers do each year. If they recommend leaving the shots unchanged — and the FDA agrees — it’s possible that healthy adults and children may still get access to a fall booster, since this week’s policy changes suggest new studies would be required only if manufacturers switch strains or introduce a completely new vaccine. Those would be large, six-month studies, and vaccine experts question if their cost and logistics could make them unfeasible.

Still, the FDA’s strain decision normally isn’t the final word on recommendations about who should be vaccinated.

The Centers for Disease Control and Prevention’s own advisory panel meets in June to make recommendations about the fall shots. Among its options are keeping universal access or recommending vaccination for high-risk groups but still giving lower-risk people the choice in getting a shot.

Prasad and FDA Commissioner Marty Makary were both outspoken critics of the government’s handling of COVID-19 shots during the pandemic, particularly the recommendation for use in young, healthy adults and children. Before joining government, they each garnered attention from Health Secretary Robert F. Kennedy Jr., who built a national following by casting doubt on the safety and benefits of vaccines.

In a medical journal editorial outlining the FDA’s new approach, they criticized the U.S.’s “one-size-fits-all” approach, saying it has long been out of step with Europe and other places with more limited recommendations for boosters.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.