* having a history of severe allergy, such as severe allergic reactions, urticaria, angioedema; * having one of the following evidence on sars-cov-2 infection(previous tests were accepted)： * sars-cov-2 positive: reverse transcription-polymerase chain reaction (rt-pcr) and/or next generation sequencing (ngs) * previous viral gene sequencing showed high homology with the known sars-cov-2 * positive specific antibody igm or igg against serum sars-cov-2 * having a history of severe allergies, such as severe allergic reactions, urticaria, angioedema; * having active infection or fever before to enrollment(≥ 37.3℃) * having primary disease in main organs, such as heart, lung, kidney, liver, nervous system, gastrointestinal system dysfunction, history of thrombocytopenia or abnormal bleeding * suffering from autoimmune diseases or a history of autoimmune diseases (such as systemic lupus erythematosus, thyroid inflammation, vasculitis, etc.) * within 7 days prior to the first dose of scta01/placebo, subject has received any prescription drugs, non-prescription drugs, chinese herbal medicines and health products * within 3 months prior to the first dose of scta01/placebo, subjects who participated in other clinical study, or remaining in the elimination period of the drug (within 5 half-lives) before treatment * within 30 days prior to the first dose of scta01/placebo, subjects who have received vaccine * within 3 months prior to the first dose of scta01/placebo, subjects who have received blood product treatment or blood donation and hemorrhage ≥400ml, or subjects who has a blood donation plan within 3 months after treatment * within 6 months prior to the first dose of scta01/placebo, subjects who have received major surgery, or has surgery plan during clinical trail * pregnant or lactating women or positive β-hcg, has plan of pregnancy from informed consent signed to 6 months after administration of scta01/placebo * positive of anti-hiv, tp-ab, anti-hcv, anti-hbv * having a history of epilepsy * having a history of malignancies * within 3 months prior to screening, sujects who have drunk more than 14 standard units (1 standard unit contains 14g alcohol, such as 360ml beer, 45ml spirits with 40% alcohol or 150ml wine), or positive of alcohol breath test * within 3 months prior to screening, subjects who smoked more than 5 cigarettes per day, do not accept smoking cessation during the study * having a history of drug addiction and drug abuse; or who have a positive urine test result for drug abuse; or cannot guarantee that they will not abuse drugs during the study * subjects who are not able to follow the plan to complete the study * subjects who are not considered suitable for the study by investigators

* having a history of severe allergy, such as severe allergic reactions, urticaria, angioedema; * having one of the following evidence on sars-cov-2 infection(previous tests were accepted)： * sars-cov-2 positive: reverse transcription-polymerase chain reaction (rt-pcr) and/or next generation sequencing (ngs) * previous viral gene sequencing showed high homology with the known sars-cov-2 * positive specific antibody igm or igg against serum sars-cov-2 * having a history of severe allergies, such as severe allergic reactions, urticaria, angioedema; * having active infection or fever before to enrollment(≥ 37.3℃) * having primary disease in main organs, such as heart, lung, kidney, liver, nervous system, gastrointestinal system dysfunction, history of thrombocytopenia or abnormal bleeding * suffering from autoimmune diseases or a history of autoimmune diseases (such as systemic lupus erythematosus, thyroid inflammation, vasculitis, etc.) * within 7 days prior to the first dose of scta01/placebo, subject has received any prescription drugs, non-prescription drugs, chinese herbal medicines and health products * within 3 months prior to the first dose of scta01/placebo, subjects who participated in other clinical study, or remaining in the elimination period of the drug (within 5 half-lives) before treatment * within 30 days prior to the first dose of scta01/placebo, subjects who have received vaccine * within 3 months prior to the first dose of scta01/placebo, subjects who have received blood product treatment or blood donation and hemorrhage ≥400ml, or subjects who has a blood donation plan within 3 months after treatment * within 6 months prior to the first dose of scta01/placebo, subjects who have received major surgery, or has surgery plan during clinical trail * pregnant or lactating women or positive β-hcg, has plan of pregnancy from informed consent signed to 6 months after administration of scta01/placebo * positive of anti-hiv, tp-ab, anti-hcv, anti-hbv * having a history of epilepsy * having a history of malignancies * within 3 months prior to screening, sujects who have drunk more than 14 standard units (1 standard unit contains 14g alcohol, such as 360ml beer, 45ml spirits with 40% alcohol or 150ml wine), or positive of alcohol breath test * within 3 months prior to screening, subjects who smoked more than 5 cigarettes per day, do not accept smoking cessation during the study * having a history of drug addiction and drug abuse; or who have a positive urine test result for drug abuse; or cannot guarantee that they will not abuse drugs during the study * subjects who are not able to follow the plan to complete the study * subjects who are not considered suitable for the study by investigators

- having a history of severe allergy, such as severe allergic reactions, urticaria, angioedema; - having one of the following evidence on sars-cov-2 infection(previous tests were accepted)： - sars-cov-2 positive: reverse transcription-polymerase chain reaction (rt-pcr) and/or next generation sequencing (ngs) - previous viral gene sequencing showed high homology with the known sars-cov-2 - positive specific antibody igm or igg against serum sars-cov-2 - having a history of severe allergies, such as severe allergic reactions, urticaria, angioedema; - having active infection or fever before to enrollment(≥ 37.3℃) - having primary disease in main organs, such as heart, lung, kidney, liver, nervous system, gastrointestinal system dysfunction, history of thrombocytopenia or abnormal bleeding - suffering from autoimmune diseases or a history of autoimmune diseases (such as systemic lupus erythematosus, thyroid inflammation, vasculitis, etc.) - within 7 days prior to the first dose of scta01/placebo, subject has received any prescription drugs, non-prescription drugs, chinese herbal medicines and health products - within 3 months prior to the first dose of scta01/placebo, subjects who participated in other clinical study, or remaining in the elimination period of the drug (within 5 half-lives) before treatment - within 30 days prior to the first dose of scta01/placebo, subjects who have received vaccine - within 3 months prior to the first dose of scta01/placebo, subjects who have received blood product treatment or blood donation and hemorrhage ≥400ml, or subjects who has a blood donation plan within 3 months after treatment - within 6 months prior to the first dose of scta01/placebo, subjects who have received major surgery, or has surgery plan during clinical trail - pregnant or lactating women or positive β-hcg, has plan of pregnancy from informed consent signed to 6 months after administration of scta01/placebo - positive of anti-hiv, tp-ab, anti-hcv, anti-hbv - having a history of epilepsy - having a history of malignancies - within 3 months prior to screening, sujects who have drunk more than 14 standard units (1 standard unit contains 14g alcohol, such as 360ml beer, 45ml spirits with 40% alcohol or 150ml wine), or positive of alcohol breath test - within 3 months prior to screening, subjects who smoked more than 5 cigarettes per day, do not accept smoking cessation during the study - having a history of drug addiction and drug abuse; or who have a positive urine test result for drug abuse; or cannot guarantee that they will not abuse drugs during the study - subjects who are not able to follow the plan to complete the study - subjects who are not considered suitable for the study by investigators

- having a history of severe allergy, such as severe allergic reactions, urticaria, angioedema; - having one of the following evidence on sars-cov-2 infection(previous tests were accepted)： - sars-cov-2 positive: reverse transcription-polymerase chain reaction (rt-pcr) and/or next generation sequencing (ngs) - previous viral gene sequencing showed high homology with the known sars-cov-2 - positive specific antibody igm or igg against serum sars-cov-2 - having a history of severe allergies, such as severe allergic reactions, urticaria, angioedema; - having active infection or fever before to enrollment(≥ 37.3℃) - having primary disease in main organs, such as heart, lung, kidney, liver, nervous system, gastrointestinal system dysfunction, history of thrombocytopenia or abnormal bleeding - suffering from autoimmune diseases or a history of autoimmune diseases (such as systemic lupus erythematosus, thyroid inflammation, vasculitis, etc.) - within 7 days prior to the first dose of scta01/placebo, subject has received any prescription drugs, non-prescription drugs, chinese herbal medicines and health products - within 3 months prior to the first dose of scta01/placebo, subjects who participated in other clinical study, or remaining in the elimination period of the drug (within 5 half-lives) before treatment - within 30 days prior to the first dose of scta01/placebo, subjects who have received vaccine - within 3 months prior to the first dose of scta01/placebo, subjects who have received blood product treatment or blood donation and hemorrhage ≥400ml, or subjects who has a blood donation plan within 3 months after treatment - within 6 months prior to the first dose of scta01/placebo, subjects who have received major surgery, or has surgery plan during clinical trail - pregnant or lactating women or positive β-hcg, has plan of pregnancy from informed consent signed to 6 months after administration of scta01/placebo - positive of anti-hiv, tp-ab, anti-hcv, anti-hbv - having a history of epilepsy - having a history of malignancies - within 3 months prior to screening, sujects who have drunk more than 14 standard units (1 standard unit contains 14g alcohol, such as 360ml beer, 45ml spirits with 40% alcohol or 150ml wine), or positive of alcohol breath test - within 3 months prior to screening, subjects who smoked more than 5 cigarettes per day, do not accept smoking cessation during the study - having a history of drug addiction and drug abuse; or who have a positive urine test result for drug abuse; or cannot guarantee that they will not abuse drugs during the study - subjects who are not able to follow the plan to complete the study - subjects who are not considered suitable for the study by investigators