inclusion criteria: - adults aged 18-90 - confirmed laboratory covid-19 infection by rt-pcr - meeting severe or critical criteria of covid-19 infection as defined at treating hospital - confirmed pneumonia by chest radiograph or computed tomography - fever defined as temperature ≥ 36.6 °c armpit, ≥ 37.2 °c oral, or ≥ 37.8 °c rectal - oxygen saturation less than 92%

inclusion criteria: - adults aged 18-90 - confirmed laboratory covid-19 infection by rt-pcr - meeting severe or critical criteria of covid-19 infection as defined at treating hospital - confirmed pneumonia by chest radiograph or computed tomography - fever defined as temperature ≥ 36.6 °c armpit, ≥ 37.2 °c oral, or ≥ 37.8 °c rectal - oxygen saturation less than 92%