inclusion criteria: - confirmation of 2019-ncov infection by rt-pcr - diagnosis of ards according to the berlin definition of ards - requiring supplemental oxygen - pneumonia that is judged by chest radiograph or ct - pao2/oxygen absorption concentration (fio2) ≤ 300mmhg - pulmonary imaging shows that the focused progress > 50% in 24-48 hours - mild to moderate 2019-ncov pneumonia/ stay in the icu <48 hours - sofa score between 2-3 point

inclusion criteria: - confirmation of 2019-ncov infection by rt-pcr - diagnosis of ards according to the berlin definition of ards - requiring supplemental oxygen - pneumonia that is judged by chest radiograph or ct - pao2/oxygen absorption concentration (fio2) ≤ 300mmhg - pulmonary imaging shows that the focused progress > 50% in 24-48 hours - mild to moderate 2019-ncov pneumonia/ stay in the icu <48 hours - sofa score between 2-3 point