By Robert Langreth & Fiona Rutherford

The Covid-19 vaccine booster shot proposed by Pfizer Inc. and BioNTech SE should be given to a smaller group of people who are the most vulnerable to serious disease, a panel of expert advisers to the U.S. Food and Drug Administration said.

The FDA and Pfizer had originally proposed approving a booster shot for everyone 16 and older. But the advisers rejected that idea out of concern that the data to support such a broad application was thin and there could be risks, especially for younger people.

Instead, the panel voted 18-0 in favor of an emergency-use authorization -- a more limited clearance than a full approval -- for people 65 and older or individuals at high risk of severe Covid-19.

The move is a setback to a sweeping plan from the Biden administration to roll out booster shots to a broad population next week. But it will still allow U.S. health officials to target third doses at people at highest risk of getting seriously ill or dying from Covid-19.

The FDA will still need to grant a final clearance. And an outside advisory panel to the Centers for Disease Control and Prevention will also make detailed recommendations for the use of the booster shot at a meeting next week.