When former New York Times journalist Dan Koeppel texted his cousin Robert Meyer, a twenty-year veteran of the emergency room at Montefiore Medical Center in the Bronx, at the beginning of the Covid-19 crisis in the United States, he expected to hear that things were hectic. On a scale of 1 to 10, 10 being overwhelmed, where do you think you are? Koeppel asked. Meyer’s grave reply—100—was merely the cusp of the crisis that would soon touch every...