A Clinical Trial of Recombinant COVID-19 Bivalent (XBB+Prototype) Protein Vaccine (Sf9 Cell) in Booster Vaccination to evaluate safety and immunogenicity in healthy population aged 18 years old and above.

To evaluate safety of Recombinant COVID-19 Bivalent (XBB+Prototype) Protein Vaccine (Sf9 Cell) (WSK-V101C) and immunogenicity superiority of WSK-V101C to Recombinant COVID-19 vaccine (WSK-V101) after booster.

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.