Primary (Day 10):
changes in the ratio of PaO2 to FiO2 from baseline
Secondary (up to 30 days):
PaO2, blood oxygen saturation (SpO2), clinical status rating on the 7‐point ordinal scale, time to clinical improvement, duration (hours) of noninvasive mechanical ventilation or high‐flow nasal catheter oxygen inhalation use, duration (hours) of invasive mechanical ventilation use, duration (hours) of extracorporeal membrane oxygenation (ECMO) use, duration (days) of oxygen use, The proportion of the patients reporting 2019‐nCoV RT‐PCR negativity at Day 10 after treatment, the counts/percentage of lymphocyte, time to hospital discharge with clinical recovery from the randomization, the incidence of critical status conversion in 30 days, all‐cause mortality within 30 days, frequency of severe adverse drug events