inclusion criteria: - healthy and covid-19-positive volunteers - the interval between the onset of symptoms and randomized is within 7 days in covid-19 patients. 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 negative; - sign the informed consent voluntarily;

inclusion criteria: - healthy and covid-19-positive volunteers - the interval between the onset of symptoms and randomized is within 7 days in covid-19 patients. 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 negative; - sign the informed consent voluntarily;