1.Patients had history of COVID-19 or COVID-19 prophylactic drugs (e.g., history of any Novel Coronavirus vaccines marketed or not marketed), 2.Patients are tested positive for SARS-CoV-2 by etiological detection (RT-PCR). Subjects who are tested positive for IgG and/or IgM antibodies could be enrolled, 3.Patients had infection or disease history of human coronaviruses including SARS and MERS, 4.Patients have fever (axillary temperature >=37.3 degree C) on the day of Dose 1 or within recent 72 hours, 5.Females in pregnancy (e.g., those with positive pregnancy test results) or lactation period, 6.Planned pregnancy or interruption of effective contraceptive measures within 3 months after Dose 2 in this clinical trial, 7.Staff of the research institution and sponsor, 8.Patients have history of anaphylaxis or allergic reactions to any vaccine or drug, such as allergy, urticaria, severe skin eczema, dyspnea, laryngeal edema, angioneurotic edema, etc., 9.Patients have been vaccinated with any vaccine within 28 days prior to the administration of Dose 1 in this study, 10.Patients have participated in or plan to participate in any clinical trials for other drugs from 28 days prior to the administration of Dose 1 to 12 months post Dose 2 in this study, 11.Patients have hereditary hemorrhagic tendency or coagulation dysfunction (such as cytokine deficiency, coagulation disorder or platelet disorder), or have a history of severe bleeding, or have a history of injuries caused by intramuscular injection or venipuncture, 12.Based on known history or diagnosis, those who are confirmed to have diseases that affect functions of the immune system, including cancer (except for basal cell carcinoma of the skin), congenital or acquired immunodeficiency (such as HIV infection), and uncontrollable autoimmune diseases, 13.Patients have asplenia or functional asplenia, 14.Patients are on long-term (continuous use for >= 14 days) immunosuppressants or other immunomodulators (e.g., glucocorticoids: prednisone or similar drugs) within 6 months prior to the administration of Dose 1 in this study. Topical application (e.g., ointment, eye drops, inhalants or nasal sprays) is allowed. Dosage for topical medication should not exceed the recommended dose in the prescribing information, 15.Patients have received immunoglobulin and/or blood products within 3 months prior to the administration of Dose 1 in this study, 16.Patients have suspected or known alcohol dependence or drug abuse, which may have an impact on the safety evaluation or the subjects compliance, 17.Patients permanently move away from the study area prior to the end of the study or those who are away from the study area over a long period of time during the study follow-up, 18.Other factors that the investigator considered inappropriate for participation in the study.

1.Patients had history of COVID-19 or COVID-19 prophylactic drugs (e.g., history of any Novel Coronavirus vaccines marketed or not marketed), 2.Patients are tested positive for SARS-CoV-2 by etiological detection (RT-PCR). Subjects who are tested positive for IgG and/or IgM antibodies could be enrolled, 3.Patients had infection or disease history of human coronaviruses including SARS and MERS, 4.Patients have fever (axillary temperature >=37.3 degree C) on the day of Dose 1 or within recent 72 hours, 5.Females in pregnancy (e.g., those with positive pregnancy test results) or lactation period, 6.Planned pregnancy or interruption of effective contraceptive measures within 3 months after Dose 2 in this clinical trial, 7.Staff of the research institution and sponsor, 8.Patients have history of anaphylaxis or allergic reactions to any vaccine or drug, such as allergy, urticaria, severe skin eczema, dyspnea, laryngeal edema, angioneurotic edema, etc., 9.Patients have been vaccinated with any vaccine within 28 days prior to the administration of Dose 1 in this study, 10.Patients have participated in or plan to participate in any clinical trials for other drugs from 28 days prior to the administration of Dose 1 to 12 months post Dose 2 in this study, 11.Patients have hereditary hemorrhagic tendency or coagulation dysfunction (such as cytokine deficiency, coagulation disorder or platelet disorder), or have a history of severe bleeding, or have a history of injuries caused by intramuscular injection or venipuncture, 12.Based on known history or diagnosis, those who are confirmed to have diseases that affect functions of the immune system, including cancer (except for basal cell carcinoma of the skin), congenital or acquired immunodeficiency (such as HIV infection), and uncontrollable autoimmune diseases, 13.Patients have asplenia or functional asplenia, 14.Patients are on long-term (continuous use for >= 14 days) immunosuppressants or other immunomodulators (e.g., glucocorticoids: prednisone or similar drugs) within 6 months prior to the administration of Dose 1 in this study. Topical application (e.g., ointment, eye drops, inhalants or nasal sprays) is allowed. Dosage for topical medication should not exceed the recommended dose in the prescribing information, 15.Patients have received immunoglobulin and/or blood products within 3 months prior to the administration of Dose 1 in this study, 16.Patients have suspected or known alcohol dependence or drug abuse, which may have an impact on the safety evaluation or the subjects compliance, 17.Patients permanently move away from the study area prior to the end of the study or those who are away from the study area over a long period of time during the study follow-up, 18.Other factors that the investigator considered inappropriate for participation in the study.

Subjects who meet any of the following exclusion criteria should be excluded from the study: 1. Those who had history of COVID-19 or COVID-19 prophylactic drugs (e.g., any history of COVID-19 vaccine that has been listed or not), 2. Those who are tested positive for SARS-CoV-2 by etiological detection (RT-PCR). Subjects who are tested positive for IgG and/or IgM antibodies could be enrolled, 3. Those who had infection or disease history of human coronaviruses including SARS and MERS, 4. Those who have fever (axillary temperature >=37.3 degree C) on the day of Dose 1 or within recent 72 hours, 5. Females in pregnancy (e.g., those with positive pregnancy test results) or lactation period, 6. Planned pregnancy or interruption of effective contraceptive measures within 3 months after Dose 2 in this clinical trial, 7. Personnel from the study site or Sponsor, 8. Those who have history of anaphylaxis or allergic reactions to any vaccine or drug, such as allergy, urticaria, severe skin eczema, dyspnea, laryngeal edema, angioneurotic edema, etc., 9. Those who have been vaccinated with any vaccine within 28 days prior to the administration of Dose 1 in this study, 10. Those who have participated in or plan to participate in any clinical trials for other drugs from 28 days prior to the administration of Dose 1 to 12 months post Dose 2 in this study, 11. Those who have hereditary hemorrhagic tendency or coagulation dysfunction (such as cytokine deficiency, coagulation disorder or platelet disorder), or have a history of severe bleeding, or have a history of injuries caused by intramuscular injection or venipuncture, 12. Based on known history or diagnosis, those who are confirmed to have diseases that affect functions of the immune system, including cancer (except for basal cell carcinoma of the skin), congenital or acquired immunodeficiency (such as HIV infection), and uncontrollable autoimmune diseases, 13. Those who have asplenia or functional asplenia, 14. Those who are on long-term (continuous use for >= 14 days) immunosuppressants or other immunomodulators (e.g., glucocorticoids: prednisone or similar drugs) within 6 months prior to the administration of Dose 1 in this study. Topical application (e.g., ointment, eye drops, inhalants or nasal sprays) is allowed. Dosage for topical medication should not exceed the recommended dose in the prescribing information, 15. Those who have received immunoglobulin and/or blood products within 3 months prior to the administration of Dose 1 in this study, 16. Those who have suspected or known alcohol dependence or drug abuse, which may have an impact on the safety evaluation or the subjects compliance, 17. Those who permanently move away from the study area prior to the end of the study or those who are away from the study area over a long period of time during the study follow-up, 18. Those who have any other conditions that, in the opinion of the investigators, precludes study participation.

Subjects who meet any of the following exclusion criteria should be excluded from the study: 1. Those who had history of COVID-19 or COVID-19 prophylactic drugs (e.g., any history of COVID-19 vaccine that has been listed or not), 2. Those who are tested positive for SARS-CoV-2 by etiological detection (RT-PCR). Subjects who are tested positive for IgG and/or IgM antibodies could be enrolled, 3. Those who had infection or disease history of human coronaviruses including SARS and MERS, 4. Those who have fever (axillary temperature >=37.3 degree C) on the day of Dose 1 or within recent 72 hours, 5. Females in pregnancy (e.g., those with positive pregnancy test results) or lactation period, 6. Planned pregnancy or interruption of effective contraceptive measures within 3 months after Dose 2 in this clinical trial, 7. Personnel from the study site or Sponsor, 8. Those who have history of anaphylaxis or allergic reactions to any vaccine or drug, such as allergy, urticaria, severe skin eczema, dyspnea, laryngeal edema, angioneurotic edema, etc., 9. Those who have been vaccinated with any vaccine within 28 days prior to the administration of Dose 1 in this study, 10. Those who have participated in or plan to participate in any clinical trials for other drugs from 28 days prior to the administration of Dose 1 to 12 months post Dose 2 in this study, 11. Those who have hereditary hemorrhagic tendency or coagulation dysfunction (such as cytokine deficiency, coagulation disorder or platelet disorder), or have a history of severe bleeding, or have a history of injuries caused by intramuscular injection or venipuncture, 12. Based on known history or diagnosis, those who are confirmed to have diseases that affect functions of the immune system, including cancer (except for basal cell carcinoma of the skin), congenital or acquired immunodeficiency (such as HIV infection), and uncontrollable autoimmune diseases, 13. Those who have asplenia or functional asplenia, 14. Those who are on long-term (continuous use for >= 14 days) immunosuppressants or other immunomodulators (e.g., glucocorticoids: prednisone or similar drugs) within 6 months prior to the administration of Dose 1 in this study. Topical application (e.g., ointment, eye drops, inhalants or nasal sprays) is allowed. Dosage for topical medication should not exceed the recommended dose in the prescribing information, 15. Those who have received immunoglobulin and/or blood products within 3 months prior to the administration of Dose 1 in this study, 16. Those who have suspected or known alcohol dependence or drug abuse, which may have an impact on the safety evaluation or the subjects compliance, 17. Those who permanently move away from the study area prior to the end of the study or those who are away from the study area over a long period of time during the study follow-up, 18. Those who have any other conditions that, in the opinion of the investigators, precludes study participation.