Fig. 2.

Progression from COVID-19 to PASC and ME/CFS. Acute COVID-19 illness is commonly resolved fully within 2–4 weeks of infection. For a variety of reasons, a significant number of recovering individuals continue to suffer symptoms 1–6 months after infection. This heterogeneous collection of patients are commonly diagnosed with “long COVID” or the post-acute sequalae of COVID-19 (PASC). A diagnosis of ME/CFS may be made for those who fail to recover by 6 months, have no objective medical explanation for their continuing symptoms and endorse fatigue, cognitive disturbances (“brain fog”), non-restorative sleep and psychiatric symptoms. Given the early stage of recovery for many with COVID-19 related illnesses and corresponding lack of data, it is not yet clear what fraction of people will progress from PASC to ME/CFS.