WASHINGTON (AP) — The U.S. on Wednesday authorized its first update to COVID-19 vaccines, booster doses that target today's most common omicron strain. Shots could begin within days.

The move by the Food and Drug Administration tweaks the recipe of shots made by Pfizer and rival Moderna that already have saved millions of lives. The hope is that the modified boosters will blunt yet another winter surge.

"You'll see me at the front of the line," FDA vaccine chief Dr. Peter Marks told The Associated Press shortly before his agency cleared the new doses.

Until now, COVID-19 vaccines have targeted...