inclusion criteria: * laboratory (rt-pcr) confirmed covid-19 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; * white blood cells ≥ 3,500 / μl, lymphocytes ≥ 750 / μl; * human immunodeficiency virus (hiv), hepatitis b virus (hbv), hepatitis c virus (hcv) or tuberculosis (tb) test is negative; * sign the informed consent form on a voluntary basis;

inclusion criteria: * laboratory (rt-pcr) confirmed covid-19 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; * white blood cells ≥ 3,500 / μl, lymphocytes ≥ 750 / μl; * human immunodeficiency virus (hiv), hepatitis b virus (hbv), hepatitis c virus (hcv) or tuberculosis (tb) test is negative; * sign the informed consent form on a voluntary basis;

inclusion criteria: - laboratory (rt-pcr) confirmed covid-19 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; - white blood cells ≥ 3,500 / μl, lymphocytes ≥ 750 / μl; - human immunodeficiency virus (hiv), hepatitis b virus (hbv), hepatitis c virus (hcv) or tuberculosis (tb) test is negative; - sign the informed consent form on a voluntary basis;

inclusion criteria: - laboratory (rt-pcr) confirmed covid-19 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; - white blood cells ≥ 3,500 / μl, lymphocytes ≥ 750 / μl; - human immunodeficiency virus (hiv), hepatitis b virus (hbv), hepatitis c virus (hcv) or tuberculosis (tb) test is negative; - sign the informed consent form on a voluntary basis;