WHEN COVID NEVER GOES AWAY

Brian Block, M.D., noticed that some of the people coming into his clinic at the University of California, San Francisco—the one he and his colleagues created to help people recover from severe Covid—weren’t who he’d anticipated. Alongside those who had been hospitalized with Covid, which was the population he and his colleagues had expected to care for, about a quarter of the patients were people who had never been hospitalized for the disease. They’d had “mild” acute Covid—a fever, a cough that they’d recovered from quickly. But months after thinking they’d beaten the illness, they didn’t feel