inclusion criteria: ct image is characteristic of viral pneumonia; 2019-ncov infection (positive nucleic acid test) is confirmed by pathogenic test; in compliance with the 2019-ncov infection severe pneumonia diagnosis standard (according to the novel coronavirus infection pneumonia diagnosis and treatment program (trial implementation version 5) issued by the national health and medical commission, and who 2019 new coronavirus guidelines standards). it is severe if it meets any of the following: (a) increased breathing rate (≥30 beats / min), difficulty breathing, cyanosis of the lips; (b) when inhaling, means oxygen saturation ≤93%; (c) partial pressure of arterial oxygen (pao2) / fraction of inspired oxygen (fio2) ≤300 mmhg (1mmhg = 0.133kpa); 18 years old ≤ age ≤ 65 years old, regardless of gender; the patient or legal donor agrees to participate in the study and signs the informed consent.

inclusion criteria: ct image is characteristic of viral pneumonia; 2019-ncov infection (positive nucleic acid test) is confirmed by pathogenic test; in compliance with the 2019-ncov infection severe pneumonia diagnosis standard (according to the novel coronavirus infection pneumonia diagnosis and treatment program (trial implementation version 5) issued by the national health and medical commission, and who 2019 new coronavirus guidelines standards). it is severe if it meets any of the following: (a) increased breathing rate (≥30 beats / min), difficulty breathing, cyanosis of the lips; (b) when inhaling, means oxygen saturation ≤93%; (c) partial pressure of arterial oxygen (pao2) / fraction of inspired oxygen (fio2) ≤300 mmhg (1mmhg = 0.133kpa); 18 years old ≤ age ≤ 65 years old, regardless of gender; the patient or legal donor agrees to participate in the study and signs the informed consent.

inclusion criteria: 1. ct image is characteristic of viral pneumonia; 2. 2019-ncov infection (positive nucleic acid test) is confirmed by pathogenic test; 3. in compliance with the 2019-ncov infection severe pneumonia diagnosis standard (according to the novel coronavirus infection pneumonia diagnosis and treatment program (trial implementation version 5) issued by the national health and medical commission, and who 2019 new coronavirus guidelines standards). it is severe if it meets any of the following: (a) increased breathing rate (≥30 beats / min), difficulty breathing, cyanosis of the lips; (b) when inhaling, means oxygen saturation ≤93%; (c) partial pressure of arterial oxygen (pao2) / fraction of inspired oxygen (fio2) ≤300 mmhg (1mmhg = 0.133kpa); 4. 18 years old ≤ age ≤ 65 years old, regardless of gender; 5. the patient or legal donor agrees to participate in the study and signs the informed consent.

inclusion criteria: 1. ct image is characteristic of viral pneumonia; 2. 2019-ncov infection (positive nucleic acid test) is confirmed by pathogenic test; 3. in compliance with the 2019-ncov infection severe pneumonia diagnosis standard (according to the novel coronavirus infection pneumonia diagnosis and treatment program (trial implementation version 5) issued by the national health and medical commission, and who 2019 new coronavirus guidelines standards). it is severe if it meets any of the following: (a) increased breathing rate (≥30 beats / min), difficulty breathing, cyanosis of the lips; (b) when inhaling, means oxygen saturation ≤93%; (c) partial pressure of arterial oxygen (pao2) / fraction of inspired oxygen (fio2) ≤300 mmhg (1mmhg = 0.133kpa); 4. 18 years old ≤ age ≤ 65 years old, regardless of gender; 5. the patient or legal donor agrees to participate in the study and signs the informed consent.