Inclusion Criteria:

1. Subjects aged 18 years and above, including those with underlying diseases and
immunocompromised subjects.

2. Basic or booster immunization with COVID-19 vaccine ≥6 months.

3. ≥3 months of SARS-CoV-2 infection history, or never infected.

4. Have the ability to understand research procedures, with informed consent, voluntarily
sign informed consent, and be able to comply with the requirements of clinical
research protocols.

Exclusion Criteria:

1. Axillary temperature ≥37.3℃.

2. SARS-CoV-2 antigen or nucleic acid screening positive within the last 48 hours.

3. Anti-SARS-CoV-2 IgM antibody was positive during the screening period.

4. It is in the advanced stage of malignant tumor and the disease control is unstable.

5. Female pregnancy (pregnancy test results are positive), lactation period.

6. Have serious cardiovascular diseases, such as arrhythmia, conduction block, myocardial
infarction, heart failure, severe hypertension, and can not be controlled by drugs.

7. Have other serious chronic conditions such as uncontrolled asthma, diabetes, chronic
obstructive pulmonary disease, pulmonary embolism, chronic kidney disease requiring
dialysis, cirrhosis of the liver, convulsions, epilepsy and other
neurological/psychiatric conditions.

8. Have been diagnosed with congenital or acquired immunodeficiency, HIV infection.

9. People who are allergic to any component of the investigational vaccine have a history
of more severe allergies or allergic reactions to the vaccine in the past.

10. Congenital or acquired angioedema/neuroedema.

11. Asplenia or functional asplenia.

12. Thrombocytopenia or other clotting disorders (which may cause intramuscular injection
contraindications).

13. Received another investigational drug within 1 month prior to receiving the
investigational vaccine.

14. Received subunit or inactivated vaccine within 14 days prior to receiving the
investigational vaccine, or received live attenuated vaccine within 1 month.

15. Fertile female subjects did not use effective contraception within 1 month prior to
enrollment.

16. Fertile female and male subjects have pregnancy plans and sperm/egg donation plans
from the screening period to 3 months after immunization.

17. Abnormal laboratory test results during the screening period, which were judged by the
researcher to be unsuitable for the study vaccine.

18. Medical, psychological, social, or other conditions that, in the investigator's
judgment, are inconsistent with the protocol or affect the subject's signing of
informed consent.