2.7 Exclusion criteria
Following patients were excluded from the study:
  1. Patients with negative detection of novel coronavirus nucleic acid.
  2. Patients in whom monitoring of blood oxygen saturation (SpO2 or PaO2) was not feasible due to any reason.
  3. Patients with suspected bacterial pneumonia (confirmed by sputum bacterial culture).
  4. Patients with interstitial pneumonia (previously diagnosed based on radiological findings).
  5. Patients with heart failure associated with pulmonary edema (non-COVID-19 heart disease).
  6. Patients with allergic pneumonia (acute or chronic eosinophilic pneumonia).
  7. Patients with active lung tumors.
  8. Patients on immunosuppressive drugs (including long-term steroids).
  9. Patients with incomplete chest computed tomography (CT) examination due to any reason.
  10. Patient refusal to be enrolled in the study.