inclusion criteria: subjects enrolled in the trial must meet all of the following criteria. * confirmed covid-19 pneumonia * hypoxia as defined by room air oxygen saturation less than 92% or supplemental oxygen requirement * presence of at least one additional biomarker that has been shown to predict poor prognosis: a) serum ferritin ≥500ug/l, b) ldh ≥250u/l, c) d-dimer ≥1ug/l, or d) lymphopenia as defined by absolute lymphocyte count \<1,000/ul * age ≥ 18 years * completed informed consent

inclusion criteria: subjects enrolled in the trial must meet all of the following criteria. * confirmed covid-19 pneumonia * hypoxia as defined by room air oxygen saturation less than 92% or supplemental oxygen requirement * presence of at least one additional biomarker that has been shown to predict poor prognosis: a) serum ferritin ≥500ug/l, b) ldh ≥250u/l, c) d-dimer ≥1ug/l, or d) lymphopenia as defined by absolute lymphocyte count \<1,000/ul * age ≥ 18 years * completed informed consent

inclusion criteria: subjects enrolled in the trial must meet all of the following criteria. - confirmed covid-19 pneumonia - hypoxia as defined by room air oxygen saturation less than 92% or supplemental oxygen requirement - presence of at least one additional biomarker that has been shown to predict poor prognosis: a) serum ferritin ≥500ug/l, b) ldh ≥250u/l, c) d-dimer ≥1ug/l, or d) lymphopenia as defined by absolute lymphocyte count <1,000/ul - age ≥ 18 years - completed informed consent

inclusion criteria: subjects enrolled in the trial must meet all of the following criteria. - confirmed covid-19 pneumonia - hypoxia as defined by room air oxygen saturation less than 92% or supplemental oxygen requirement - presence of at least one additional biomarker that has been shown to predict poor prognosis: a) serum ferritin ≥500ug/l, b) ldh ≥250u/l, c) d-dimer ≥1ug/l, or d) lymphopenia as defined by absolute lymphocyte count <1,000/ul - age ≥ 18 years - completed informed consent