WASHINGTON — Government advisers are debating whether to recommend extra doses of the Pfizer vaccine, a key step toward the Biden administration’s plan to dispense COVID-19 booster shots to most Americans.

Scientists inside and outside the U.S. government have been divided in recent days over the need for boosters and who should get them. A panel of Food and Drug Administration advisers will vote Friday on the safety and effectiveness of boosters.

This week, two top FDA vaccine reviewers joined a group of international scientists in publishing an editorial rejecting the need for boosters in healthy people. The scientists said continuing studies show the shots are working well despite the delta variant.

If the FDA approves the extra doses, a separate committee convened by the Centers for Disease Control and Prevention will debate who should get boosters and when.

The World Health Organization has strongly objected to rich nations giving a third round of shots when poor countries don’t have enough vaccine for their first.