Daniel Griffin, an infectious disease specialist, was standing with a group of physicians outside the doors of the intensive care unit at Plainview Hospital on Long Island, N.Y., in late February. Layered in protective gowns, masks, and gloves and standing six feet apart to maintain social distancing, the doctors swapped stories about their COVID-19 patients. Griffin brought up a disturbing trend: Many of his patients seemed on their way to recovery but then relapsed into severe respiratory distress. His colleagues had seen a similar pattern. The fluctuation of symptoms was puzzling for a virus.
Then the doctors had an insight: shortness of breath, chest pain and rapid heart rate are also signs of a pulmonary embolism, a blood clot that lodges in the arteries