WASHINGTON (NewsNation Now) — A panel of expert outside advisers to the U.S. Food and Drug Administration voted against approving COVID-19 booster shots for most Americans, but it endorsed the extra shots for those who are 65 or older or run a high risk of severe disease.

The panel voted 16-2 against approving boosters for Americans age 16 and older. The twin votes Friday potentially undermine the Biden administration’s plan to roll out third shots of the Pfizer/BioNTech vaccine as soon as next week.

Then, in an 18-0 vote, it endorsed the extra shot for select portions of the U.S. population — namely, those most at risk from the virus.

Over several hours of discussion, members of the FDA panel voiced frustration that Pfizer had provided little data on the safety of extra doses.

Many committee members were critical of the booster plan, arguing that the data presented by Pfizer and the FDA is incomplete and that the request for approval for people as young 16 years old is too broad. Most of them said they would support boosters for older Americans, but did not think they were needed yet for younger adults.

Top FDA members have been split on the necessity of the boosters, with interim head Janet Woodcock backing them and some of the agency’s top scientists arguing they are not needed yet.

This panel is not the deciding body. The FDA can go against the recommendation they provide.

If the FDA approves the booster, a separate panel advising the U.S. Centers for Disease Control and Prevention will meet next week to recommend which groups should get them.

The White House said it was ready to roll out boosters next week if health officials approve the plan.