LOS ANGELES - Dr. Anthony Fauci, the nation’s top infectious disease expert, said he feels confident in current indications of the enduring efficacy of COVID-19 vaccines, but Fauci said that there’s a worrisome "wild card" factoring into the calculation of whether booster shots will be needed down the road: emerging coronavirus variants.In an interview with FOX Television Stations Tuesday, Fauci said divergent mutations of the virus present challenges in the race to vaccinate, but until there is conclusive evidence indicating the need for coronavirus boosters, getting a shot into the arms of as many people as possible remains the best course of action.