U.S. health officials plan to offer COVID-19 booster shots to vaccinated Americans to shore up their protection amid the surging delta variant and evidence that the vaccines’ effectiveness is declining. A look at what we know about boosters and how they could help fight the coronavirus pandemic:

Just because Pfizer wants to offer COVID-19 vaccine boosters doesn’t mean people will be lining up anytime soon -- U.S. and international health authorities say that for now, the fully vaccinated seem well protected.