Post-COVID-19 interstitial lung disease presenting with profound hypoxemia: Report of three cases demonstrating a goog response to high-dose corticosteroid therapy

SARS-CoV-2 infection sometimes causes secondary pulmonary fibrosis. Interstitial lung disease after COVID-19 is caused by excessive cytokines and abnormal repair processes by lung cells including epithelium, mesenchyme and alveolar macrophages, which is thought to be developed by lung injury rather than viral invasion itself. Immunosuppression therapy e.g. high-dose corticosteroid therapy was shown to have a good response to this post COVID-19 respiratory disease.