As public health officials race to vaccinate Americans amid the rapid spread of viral variants, physicians and scientists are turning their attention to a growing population of those who seem locked into COVID-19’s misery months after the acute phase has passed. These so-called “COVID long-haulers” or sufferers of “long COVID” are those who continue to feel symptoms long after the days or weeks that represent a typical course of the disease. These patients tend to be younger and, puzzlingly, in some cases suffered just mild initial conditions.