As of Jan 4, 2021, the global pandemic of COVID-19—an emerging infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—has resulted in more than 83 million confirmed cases with more than 1·8 million deaths. The epidemiological and clinical characteristics, pathogenesis, and complications of patients with COVID-19 at acute phase have been explicitly described, but the long-term consequences of the illness remain largely unclear.
Long-term follow-up studies on persistent symptoms, lung function, physical, and psychological problems of discharged patients are urgently required.3
Only a few studies with limited sample size have been published, with the longest follow-up duration of 3 months following discharge from hospital. Some persisting symptoms such as fatigue and dyspnoea, impaired pulmonary function, and chest image abnormalities were reported in patients following hospital discharge, but the full spectrum of post-discharge characteristics is still unknown. Furthermore, no studies have yet reported the extra-pulmonary organ manifestations that could persist after damage in acute stage or are new onset after discharge.