“There were so many unknowns at the beginning of the pandemic,” Alex Enurah, an internal-medicine-trained hospitalist at the Medical Center of Aurora, in Colorado, told me when we spoke via Zoom recently. He had a dark beard of rich gloss and density, and maintained an expression of attentive listening and kind concern. “First, will it really cross the seas to the U.S.? How hard will it hit us? Who’s going to get it?” As the virus ravaged Spain and Italy, the questions built, along with the foreboding sense “that something big was coming, with little time to prepare.”