1. Abnormal results of physical examinations which was clinically significant judged by clinicians, 2. Abnormal vital signs with clinical significance at screening, systolic blood pressure >=140 mmHg or diastolic blood pressure >=90 mmHg, or axillary body temperature > 37.3 degrees, 3. Known allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine), 4. History of human coronavirus infection/diseases, such as severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), 5. History of COVID-19 (self-reported), or history of close contact with a confirmed/suspected COVID-19 case, or positive results for either SARS-CoV-2 nucleic acid and antibody tests at screening, 6. Have taken antipyretics or pain relievers within 24 hours before the first dose of the vaccine, 7. Receipt of any COVID-19 vaccine, live attenuated vaccine within 28 days prior to vaccination and other vaccines within 14 days prior to vaccination, 8. Receipt of blood or blood-related products, including immunoglobulins, within 3 months prior to vaccination, or any planned use during the study period, 9. Subjects with the following diseases: (1) Any acute diseases or acute attacks of chronic diseases within 7 days prior to enrolment, (2) Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc., (3) A history of congenital or acquired immunodeficiency or autoimmune disease, or long-term receipt (> 14 consecutive days) of glucocorticoid (reference value for dose: >= 20 mg/day prednisone or equivalent) or other immunosuppressive agents within the past 6 months, with exception of inhaled or topical steroids, or short-term use (<= 14 consecutive days) of oral corticosteroids, (4) Currently suffering from or previously diagnosed with infectious diseases, or positive screening results for hepatitis B (HBV), hepatitis C (HCV), syphilis and human immunodeficiency virus (HIV) (only in phase II trial), (5) History or family history of neurological disorders (convulsions, epilepsy, encephalopathy, etc.) or psychiatric disorders, (6) Asplenia, and functional asplenia, (7) Presence of severe, uncontrollable or hospitalized cardiovascular diseases (or prodrome), diabetes, neurological diseases (e.g., Guillain-Barre syndrome), blood and lymphatic diseases, immune diseases, liver and kidney diseases, respiratory diseases (e.g., active tuberculosis, pulmonary fibrosis), metabolic and skeletal diseases, or malignant tumors, (8) Contraindications to IM injections and blood draws, such as coagulation disorders, thrombotic or bleeding disorders, or conditions that needs continuous anticoagulant usage, 10. Drug or alcohol abuse which in the investigators opinion would compromise the participants safety or compliance with the study procedures, 11. History of a major surgery, per the investigators judgment, within 12 weeks before vaccination, or will not have fully recovered from surgery, or has major surgery planned during the time the participant is expected to participate in the study or within 12 months after vaccine administration, 12. Pregnant or lactating females, 13. Having participated or being participating in other COVID-19 related clinical trials, 14. Presence of any underlying disease or condition which, in the opinion of the investigator, may place the subject at unacceptable risk, are unable to meet th

1. Abnormal results of physical examinations which was clinically significant judged by clinicians, 2. Abnormal vital signs with clinical significance at screening, systolic blood pressure >=140 mmHg or diastolic blood pressure >=90 mmHg, or axillary body temperature > 37.3 degrees, 3. Known allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine), 4. History of human coronavirus infection/diseases, such as severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), 5. History of COVID-19 (self-reported), or history of close contact with a confirmed/suspected COVID-19 case, or positive results for either SARS-CoV-2 nucleic acid and antibody tests at screening, 6. Have taken antipyretics or pain relievers within 24 hours before the first dose of the vaccine, 7. Receipt of any COVID-19 vaccine, live attenuated vaccine within 28 days prior to vaccination and other vaccines within 14 days prior to vaccination, 8. Receipt of blood or blood-related products, including immunoglobulins, within 3 months prior to vaccination, or any planned use during the study period, 9. Subjects with the following diseases: (1) Any acute diseases or acute attacks of chronic diseases within 7 days prior to enrolment, (2) Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc., (3) A history of congenital or acquired immunodeficiency or autoimmune disease, or long-term receipt (> 14 consecutive days) of glucocorticoid (reference value for dose: >= 20 mg/day prednisone or equivalent) or other immunosuppressive agents within the past 6 months, with exception of inhaled or topical steroids, or short-term use (<= 14 consecutive days) of oral corticosteroids, (4) Currently suffering from or previously diagnosed with infectious diseases, or positive screening results for hepatitis B (HBV), hepatitis C (HCV), syphilis and human immunodeficiency virus (HIV) (only in phase II trial), (5) History or family history of neurological disorders (convulsions, epilepsy, encephalopathy, etc.) or psychiatric disorders, (6) Asplenia, and functional asplenia, (7) Presence of severe, uncontrollable or hospitalized cardiovascular diseases (or prodrome), diabetes, neurological diseases (e.g., Guillain-Barre syndrome), blood and lymphatic diseases, immune diseases, liver and kidney diseases, respiratory diseases (e.g., active tuberculosis, pulmonary fibrosis), metabolic and skeletal diseases, or malignant tumors, (8) Contraindications to IM injections and blood draws, such as coagulation disorders, thrombotic or bleeding disorders, or conditions that needs continuous anticoagulant usage, 10. Drug or alcohol abuse which in the investigators opinion would compromise the participants safety or compliance with the study procedures, 11. History of a major surgery, per the investigators judgment, within 12 weeks before vaccination, or will not have fully recovered from surgery, or has major surgery planned during the time the participant is expected to participate in the study or within 12 months after vaccine administration, 12. Pregnant or lactating females, 13. Having participated or being participating in other COVID-19 related clinical trials, 14. Presence of any underlying disease or condition which, in the opinion of the investigator, may place the subject at unacceptable risk, are unable to meet th