inclusion criteria: * adult aged \>=18years old; * laboratory (rt-pcr) confirmed 2019-ncov infection in throat swab and/or sputum and/or lower respiratory tract samples; * the interval between the onset of symptoms and randomized is within 7 days. the onset of symptoms is mainly based on fever. if there is no fever, cough or other related symptoms can be used; * meet any of the following criteria for severe or critical ill conditions: 1. respiratory rate \>=30/min; or 2. rest spo2\<=90%; or 3. pao2/fio2\<=300mmhg; or 4. respiratory failure and needs mechanical ventilation; or 5. shock occurs; or 6. multiple organ failure and needs icu monitoring; * sign the informed consent form on a voluntary basis.

inclusion criteria: * adult aged \>=18years old; * laboratory (rt-pcr) confirmed 2019-ncov infection in throat swab and/or sputum and/or lower respiratory tract samples; * the interval between the onset of symptoms and randomized is within 7 days. the onset of symptoms is mainly based on fever. if there is no fever, cough or other related symptoms can be used; * meet any of the following criteria for severe or critical ill conditions: 1. respiratory rate \>=30/min; or 2. rest spo2\<=90%; or 3. pao2/fio2\<=300mmhg; or 4. respiratory failure and needs mechanical ventilation; or 5. shock occurs; or 6. multiple organ failure and needs icu monitoring; * sign the informed consent form on a voluntary basis.

inclusion criteria: adult aged >=18years old; laboratory (rt-pcr) confirmed 2019-ncov infection in throat swab and/or sputum and/or lower respiratory tract samples; the interval between the onset of symptoms and randomized is within 7 days. the onset of symptoms is mainly based on fever. if there is no fever, cough or other related symptoms can be used; meet any of the following criteria for severe or critical ill conditions: respiratory rate >=30/min; or rest spo2<=90%; or pao2/fio2<=300mmhg; or respiratory failure and needs mechanical ventilation; or shock occurs; or multiple organ failure and needs icu monitoring; sign the informed consent form on a voluntary basis.

inclusion criteria: adult aged >=18years old; laboratory (rt-pcr) confirmed 2019-ncov infection in throat swab and/or sputum and/or lower respiratory tract samples; the interval between the onset of symptoms and randomized is within 7 days. the onset of symptoms is mainly based on fever. if there is no fever, cough or other related symptoms can be used; meet any of the following criteria for severe or critical ill conditions: respiratory rate >=30/min; or rest spo2<=90%; or pao2/fio2<=300mmhg; or respiratory failure and needs mechanical ventilation; or shock occurs; or multiple organ failure and needs icu monitoring; sign the informed consent form on a voluntary basis.

inclusion criteria: - adult aged >=18years old; - laboratory (rt-pcr) confirmed 2019-ncov infection in throat swab and/or sputum and/or lower respiratory tract samples; - the interval between the onset of symptoms and randomized is within 7 days. the onset of symptoms is mainly based on fever. if there is no fever, cough or other related symptoms can be used; - meet any of the following criteria for severe or critical ill conditions: 1. respiratory rate >=30/min; or 2. rest spo2<=90%; or 3. pao2/fio2<=300mmhg; or 4. respiratory failure and needs mechanical ventilation; or 5. shock occurs; or 6. multiple organ failure and needs icu monitoring; - sign the informed consent form on a voluntary basis.

inclusion criteria: - adult aged >=18years old; - laboratory (rt-pcr) confirmed 2019-ncov infection in throat swab and/or sputum and/or lower respiratory tract samples; - the interval between the onset of symptoms and randomized is within 7 days. the onset of symptoms is mainly based on fever. if there is no fever, cough or other related symptoms can be used; - meet any of the following criteria for severe or critical ill conditions: 1. respiratory rate >=30/min; or 2. rest spo2<=90%; or 3. pao2/fio2<=300mmhg; or 4. respiratory failure and needs mechanical ventilation; or 5. shock occurs; or 6. multiple organ failure and needs icu monitoring; - sign the informed consent form on a voluntary basis.