A panel of the U.S. Food and Drug Administration’s vaccine advisers has voted against Pfizer‘s request to add a third booster shot to its two-dose regimen for those aged 16 and older, bringing a significant hurdle for the White House’s booster rollout.

By a vote of 16 to 3, the FDA advisory committee rejected the request to add a third dose for the general public, saying they still need more data for approval.

“It’s unclear that everyone needs to be boosted, other than a subset of the population that clearly would be at high risk for serious disease,” Dr. Michael G. Kurilla, a committee member and official at the National Institutes of Health, said on Friday.

FDA’s vaccine advisers have rejected Pfizer’s request to add booster shots for the general public. Above, an Oakland County Health Department emergency preparedness specialist fills syringes with doses of a COVID-19 vaccine on August 24, 2021, in Southfield, Michigan.
Emily Elconin/Stringer

The panel may still clear booster shots in a narrower recommendation for older populations, who are more vulnerable to severe illness due to a COVID infection, but it is unclear when a second vote could come.

The decision comes days before the Biden administration anticipated offering booster shots of both the Pfizer and Moderna vaccine.

Pending authorization from federal regulators, the White House said they would offer a third dose as early as next week for those who were first to receive their vaccines and whose immunity against COVID-19 may be waning.