NEW YORK (AP) — Despite its world-class medical system and its vaunted Centers for Disease Control and Prevention, the U.S. fell behind in the race to detect dangerous coronavirus mutations. And it’s only now beginning to catch up. The problem has not been a shortage of technology or expertise. Rather, scientists say, it’s an absence of national leadership and coordination, plus a lack of funding and supplies for overburdened laboratories trying to juggle diagnostic testing with the hunt for mutations.