FILE - A Pfizer COVID-19 vaccine booster shot is prepped to be administered at the Mount Sinai South Nassau Vaxmobile that visited Freeport High School, in Freeport, New York, on Tuesday, November 30, 2021. (Photo by Steve Pfost/Newsday RM via Getty WASHINGTON - The U.S.
is expanding COVID-19 boosters, ruling that 16- and 17-year-olds can get a third dose of Pfizer’s vaccine.The U.S. and many other nations already were urging adults to get booster shots to pump up immunity that can wane months after vaccination, calls that intensified with the discovery of the worrisome new omicron variant.RELATED: Pfizer: COVID-19 booster offers protection against omicron in early studyOn Thursday, the Food and Drug Administration gave emergency.