The Latest: US gives go-ahead for Pfizer coronavirus vaccine

WASHINGTON — The U.S. has given the final go-ahead to the nation’s first COVID-19 vaccine, marking what could be the beginning of the end of an outbreak that has killed nearly 300,000 Americans.Shots for health workers and nursing home residents are expected to begin in the coming days after the Food and Drug Administration on Friday authorized an emergency rollout of what promises to be a strongly protective vaccine from Pfizer and its German partner BioNTech.Initial doses are scarc