Profile of a killer: Unraveling the deadly new coronavirus

Countless hours of treatment and research, trial and error now make it possible to take much closer measure of the new coronavirus and the lethal disease it has unleashed. “It’s like we’re in a battle with something that we can’t see, that we don’t know, and we don’t know where it’s coming from,” said Vivian Castro, a nurse supervisor at St. Joseph’s Medical Center in Yonkers, just north of New York City, which struggled with its caseload this spring. The coronavirus is invisible, but seemingly everywhere.