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It was also reported that pulmonary function tests performed at discharge revealed no significant difference in forced expiratory volume in the first second (FEV1) or forced vital capacity (FVC) values between COVID-19 patients with mild, moderate, and severe pneumonia, whereas diffusion capacity decreased in correlation with disease severity. Pulmonary function testing is often not recommended for patients with active COVID-19 infection in order to prevent excessive transmission. However, despite clinical improvement in this patient group, ongoing hypoxia and persistent radiological findings cause considerable difficulty in predicting the extent of improvement in pulmonary function.