Differential diagnosis, investigations and treatment
The COVID-19 patients were diagnosed using polymerase chain reaction (PCR) test or quantitative antigen test. All patients underwent computed tomography (CT) at admission and on demand by the physicians. The medications for pneumonia included dexamethasone, remdesivir, and favipiravir. We used nasal cannula, oxygen mask, and high-flow nasal cannula (HFNC), but did not use ventilator or noninvasive positive pressure ventilation (NPPV). The diagnosis of pneumothorax was made using chest radiography (Figure 1) or CT (Figure 2). The requirement for obtaining informed consent from patients was waived due to the retrospective nature of the study. Patients were allowed to withdraw from the study at any time.