Labor economists have long studied a phenomenon called hysteresis: in economics, it refers to a situation in which high unemployment caused by a particular event develops an inertia of its own, remaining elevated even after the initial cause has abated. Nobody is quite sure what causes hysteresis. Do workers’ skills erode? Or do firms find that they can get along with fewer workers? In any case, now that the pandemic has caused extended mass unemployment, hysteresis could play a major role in our society—and our health care.