inclusion criteria: * (1) an age of 18 years or over (inclusive); (2) not more than five days since the development of covid-19 symptoms, and positive for nucleic acid or antigen test for covid-19 within five days before enrollment; (3) presence of at least one symptom related to covid-19 infection at the time of enrollment; (4) agreement to practice effective birth control (for females of child-bearing potential); (5) presence of at least one high risk factor for severe covid-19 infection: * age ≥ 60 years; * bmi\>25； * fever (body temperature ≥ 38℃) for ≥ 3 days; * current smokers (still being smoking within 30 days before enrollment and have used at least 100 cigarettes up to date); * immunosuppressive diseases, including but not limited to: myelosuppression or organ transplantation or primary immunodeficiency disease; prolonged use of immunosuppressive agents (≥ 20 mg/d for at least 14 days in the case of prednisone within the last 30 days); biologic therapy (such as infliximab, etc.); use of immunomodulators (including but not limited to methotrexate, azathioprine, etc.); radiotherapy and/or chemotherapy for any malignancies within 90 days (for chest radiotherapy, this time interval should be more than 6 months); * chronic lung disease (such as asthma requiring intervention daily, bronchiectasis, copd, pulmonary hypertension, osas, interstitial lung disease, etc.); * hypertension; ⑧ cardiovascular diseases (previously diagnosed as myocardial infarction or stroke, tia (transient ischemic attack), cardiac insufficiency, angina pectoris requiring nitrate therapy, cabg, post-pci, post-carotid endarterectomy and aortic bypass surgery, etc.); ⑨ type 1 or type 2 diabetes; ⑩ neurodevelopmental abnormalities (such as cerebral palsy, down's syndrome) or other genetic or metabolic syndromes and severe congenital malformations; ⑪ active tumors (excluding localized skin cancer); ⑫ no vaccination against covid-19

inclusion criteria: * (1) an age of 18 years or over (inclusive); (2) not more than five days since the development of covid-19 symptoms, and positive for nucleic acid or antigen test for covid-19 within five days before enrollment; (3) presence of at least one symptom related to covid-19 infection at the time of enrollment; (4) agreement to practice effective birth control (for females of child-bearing potential); (5) presence of at least one high risk factor for severe covid-19 infection: * age ≥ 60 years; * bmi\>25； * fever (body temperature ≥ 38℃) for ≥ 3 days; * current smokers (still being smoking within 30 days before enrollment and have used at least 100 cigarettes up to date); * immunosuppressive diseases, including but not limited to: myelosuppression or organ transplantation or primary immunodeficiency disease; prolonged use of immunosuppressive agents (≥ 20 mg/d for at least 14 days in the case of prednisone within the last 30 days); biologic therapy (such as infliximab, etc.); use of immunomodulators (including but not limited to methotrexate, azathioprine, etc.); radiotherapy and/or chemotherapy for any malignancies within 90 days (for chest radiotherapy, this time interval should be more than 6 months); * chronic lung disease (such as asthma requiring intervention daily, bronchiectasis, copd, pulmonary hypertension, osas, interstitial lung disease, etc.); * hypertension; ⑧ cardiovascular diseases (previously diagnosed as myocardial infarction or stroke, tia (transient ischemic attack), cardiac insufficiency, angina pectoris requiring nitrate therapy, cabg, post-pci, post-carotid endarterectomy and aortic bypass surgery, etc.); ⑨ type 1 or type 2 diabetes; ⑩ neurodevelopmental abnormalities (such as cerebral palsy, down's syndrome) or other genetic or metabolic syndromes and severe congenital malformations; ⑪ active tumors (excluding localized skin cancer); ⑫ no vaccination against covid-19

inclusion criteria: (1) an age of 18 years or over (inclusive); (2) not more than five days since the development of covid-19 symptoms, and positive for nucleic acid or antigen test for covid-19 within five days before enrollment; (3) presence of at least one symptom related to covid-19 infection at the time of enrollment; (4) agreement to practice effective birth control (for females of child-bearing potential); (5) presence of at least one high risk factor for severe covid-19 infection: age ≥ 60 years; bmi>25； fever (body temperature ≥ 38℃) for ≥ 3 days; current smokers (still being smoking within 30 days before enrollment and have used at least 100 cigarettes up to date); immunosuppressive diseases, including but not limited to: myelosuppression or organ transplantation or primary immunodeficiency disease; prolonged use of immunosuppressive agents (≥ 20 mg/d for at least 14 days in the case of prednisone within the last 30 days); biologic therapy (such as infliximab, etc.); use of immunomodulators (including but not limited to methotrexate, azathioprine, etc.); radiotherapy and/or chemotherapy for any malignancies within 90 days (for chest radiotherapy, this time interval should be more than 6 months); chronic lung disease (such as asthma requiring intervention daily, bronchiectasis, copd, pulmonary hypertension, osas, interstitial lung disease, etc.); hypertension; ⑧ cardiovascular diseases (previously diagnosed as myocardial infarction or stroke, tia (transient ischemic attack), cardiac insufficiency, angina pectoris requiring nitrate therapy, cabg, post-pci, post-carotid endarterectomy and aortic bypass surgery, etc.); ⑨ type 1 or type 2 diabetes; ⑩ neurodevelopmental abnormalities (such as cerebral palsy, down's syndrome) or other genetic or metabolic syndromes and severe congenital malformations; ⑪ active tumors (excluding localized skin cancer); ⑫ no vaccination against covid-19

inclusion criteria: (1) an age of 18 years or over (inclusive); (2) not more than five days since the development of covid-19 symptoms, and positive for nucleic acid or antigen test for covid-19 within five days before enrollment; (3) presence of at least one symptom related to covid-19 infection at the time of enrollment; (4) agreement to practice effective birth control (for females of child-bearing potential); (5) presence of at least one high risk factor for severe covid-19 infection: age ≥ 60 years; bmi>25； fever (body temperature ≥ 38℃) for ≥ 3 days; current smokers (still being smoking within 30 days before enrollment and have used at least 100 cigarettes up to date); immunosuppressive diseases, including but not limited to: myelosuppression or organ transplantation or primary immunodeficiency disease; prolonged use of immunosuppressive agents (≥ 20 mg/d for at least 14 days in the case of prednisone within the last 30 days); biologic therapy (such as infliximab, etc.); use of immunomodulators (including but not limited to methotrexate, azathioprine, etc.); radiotherapy and/or chemotherapy for any malignancies within 90 days (for chest radiotherapy, this time interval should be more than 6 months); chronic lung disease (such as asthma requiring intervention daily, bronchiectasis, copd, pulmonary hypertension, osas, interstitial lung disease, etc.); hypertension; ⑧ cardiovascular diseases (previously diagnosed as myocardial infarction or stroke, tia (transient ischemic attack), cardiac insufficiency, angina pectoris requiring nitrate therapy, cabg, post-pci, post-carotid endarterectomy and aortic bypass surgery, etc.); ⑨ type 1 or type 2 diabetes; ⑩ neurodevelopmental abnormalities (such as cerebral palsy, down's syndrome) or other genetic or metabolic syndromes and severe congenital malformations; ⑪ active tumors (excluding localized skin cancer); ⑫ no vaccination against covid-19