inclusion criteria: 1. age: ≥18 years old, both genders; 2. confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); 3. respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; 4. article (3) above is newly appeared within 7 days; 5. chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: 1. age: ≥18 years old, both genders; 2. confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); 3. respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; 4. article (3) above is newly appeared within 7 days; 5. chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: ≥18 years old, both genders; confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; article (3) above is newly appeared within 7 days; chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: ≥18 years old, both genders; confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; article (3) above is newly appeared within 7 days; chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: 18-80 years old, both genders; confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; and pao2/fio2>100mmhg; article (3) above is newly appeared within 7 days; chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: 18-80 years old, both genders; confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; and pao2/fio2>100mmhg; article (3) above is newly appeared within 7 days; chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: 18-80 years old, both genders; confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; and pao2/fio2>100mmhg; article (3) above is newly appeared within 5 days; chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: 18-80 years old, both genders; confirmed covid-19 diagnosis (any body fluid tested positive for sars-cov-2 nucleic acid by pcr, or positive for sars-cov-2 antigen); respiratory rate ≥ 30 times/min, partial pressure of oxygen (pao2)/ fraction of inspiration o2 (fio2)≤ 300mmhg (1mmhg = 0.133kpa), or spo2 ≤ 93% at rest without supplemental oxygen; and pao2/fio2>100mmhg; article (3) above is newly appeared within 5 days; chest radiography or computed tomography shows bilateral chest infiltrates.

inclusion criteria: age: 18-80 years old, male and female; covid-19 confirmed cases; comply with any of the following: dyspnea, rr ≥ 30 times / min; in resting state, transcutaneous oxygen saturation ≤ 93%; oxygenation index (pao2 / fio2) < 300mmhg; pulmonary imaging showed diffuse exudative lesions.

inclusion criteria: age: 18-80 years old, male and female; covid-19 confirmed cases; comply with any of the following: dyspnea, rr ≥ 30 times / min; in resting state, transcutaneous oxygen saturation ≤ 93%; oxygenation index (pao2 / fio2) < 300mmhg; pulmonary imaging showed diffuse exudative lesions.

inclusion criteria: 1. age: 18-80 years old, male and female; 2. covid-19 confirmed cases; 3. comply with any of the following: - dyspnea, rr ≥ 30 times / min; - in resting state, transcutaneous oxygen saturation ≤ 93%; - oxygenation index (pao2 / fio2) < 300mmhg; 4. pulmonary imaging showed diffuse exudative lesions.

inclusion criteria: 1. age: 18-80 years old, male and female; 2. covid-19 confirmed cases; 3. comply with any of the following: - dyspnea, rr ≥ 30 times / min; - in resting state, transcutaneous oxygen saturation ≤ 93%; - oxygenation index (pao2 / fio2) < 300mmhg; 4. pulmonary imaging showed diffuse exudative lesions.