Inclusion Criteria:

1. At the age of 18 or above, consent to participate in the study by voluntarily signing
an ICF approved by the Ethics Committee prior to the commencement of any study
procedure;

2. Subjects qualified for immunization with this product after medical history, physical
examination and clinical judgment of health;

3. Completion of 2 /3 doses of inactivated novel coronavirus vaccine ≥3 months;

4. The subject is able and willing to comply with the requirements of the clinical trial
protocol and can complete the study follow-up for approximately 12 months;

5. Armpit body temperature < 37.3℃;

6. Female non-pregnancy period (pregnancy test results are negative), non-lactation
period;

7. Fertile women (WOCBP) subjects had taken effective contraceptive measures 1 month
before enrollment;

8. WOCBP subjects and male subjects have no pregnancy plans from the screening period to
6 months after the last dose of immunization, and agree to take effective
contraceptive measures from the screening visit to 6 months after the last dose of
immunization;

9. WOCBP subjects and male subjects agree not to donate eggs (oocytes, oocytes) for
assisted reproduction (WOCBP subjects) or to refrain from sperm donation (male
subjects) for a period of 6 months from screening visit to the last dose of
immunization.

Exclusion Criteria:

1. Positive results of SARS-CoV-2 RT-PCR within 24 hours;

2. The subject has a history of SARS-CoV-2 infection within 3 months;

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

4. History of human coronavirus infection or disease with severe acute respiratory
syndrome (SARS), Middle East Respiratory Syndrome (MERS), etc.;

5. Previous history of convulsion, epilepsy, encephalopathy or psychosis or family
history;

6. Needle fainter;

7. Those who plan to become pregnant or donate sperm or eggs during the trial period
(within 6 months after exemption);

8. Previous history of allergic reaction or allergic reaction to any vaccine and its
excipients, such as allergy, urticaria, severe eczema, dyspnea, laryngeal edema,
angioneurotic edema, etc.;

9. Received subunit or inactivated vaccine within 14 days or live attenuated vaccine
within 1 month prior to receiving the experimental vaccine;

10. Participating in any other interventional test device or drug study within 30 days
prior to screening, or currently using another investigational drug or within 5
half-life after the last administration of the study drug;

11. A genetic tendency to hemorrhage or coagulation abnormalities (such as cytokine
defects, coagulation disorders or platelet disorders), or a history of severe
bleeding, or a history of excessive bleeding or ecchymosis following intramuscular
injection or venipuncture;

12. Confirmation of diseases affecting the functioning of the immune system, including
cancer, congenital or acquired immunodeficiency (e.g., human immunodeficiency virus
(HIV) infection), uncontrolled autoimmune diseases, based on known medical history or
diagnosis;

13. There are serious or uncontrollable respiratory diseases, cardiovascular diseases,
nervous system diseases, blood and lymphatic system diseases, liver and kidney
diseases, metabolic and skeletal system diseases that affect the evaluation of the
results of this study as determined by the researchers;

14. Anplenia or functional anplenia;

15. Long-term use (continuous use ≥14 days) of immunosuppressants or other
immunomodulatory drugs (such as corticosteroids: prednisone or similar drugs) within
the 6 months prior to the study vaccine, but topical use (such as ointment, eye drops,
inhalants or nasal spray) is permitted, and the topical use shall not exceed the
dosage recommended in the instructions or any systemic signs of exposure;

16. Received immunoglobulin and/or blood products in the three months prior to receiving
the study vaccine;

17. Patients undergoing anti-tuberculosis treatment;

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.