Inclusion Criteria:

1. Healthy male or female subjects aged ≥18 years of age;

2. Subjects who are in good physical condition as judged by the investigator based on
medical history, physical examination and clinical laboratory tests;

3. Subjects who have not been previously vaccinated with a Covid-19 vaccine or who have
received the last dose (total dose ≤ 3 doses) of a Covid-19 vaccine at least 6
months ago;

4. Subjects who have not been previously infected with Covid-19, or whose nucleic acid
or antigen test has turned negative for more than 1 month after previous Covid-19
infection;

5. Subjects who have used effective contraception since 2 weeks prior to enrolment;

6. Subjects or their delegates are able to understand the study procedures, have
provide written informed consent, and are able to comply with the requirements of
the clinical study protocol.

Exclusion Criteria:

1. Females of childbearing potential who have a positive pregnancy test, are pregnant,
breastfeeding, or planning to become pregnant within 12 months; males: whose spouse
is planning to become pregnant within 1 year;

2. History of epilepsy, convulsions or seizures, psychosis or family history of
psychosis;

3. Subjects who were using antipyretic, analgesic or anti-allergic drugs within 3 days
before enrolment;

4. Have a previous history of severe allergy to any medication or vaccination (e.g.
acute allergic reaction, urticaria, skin eczema, dyspnoea, angioneurotic oedema, or
abdominal pain) or allergy to known components of a Covid-19 vaccine;

5. Have a history of hospital-diagnosed thrombocytopenia or other coagulation
disorders;

6. Have a history of hospital-diagnosed known immunological impairment or hypofunction;

7. Subjects who have received immunoenhancement or immunosuppressant therapy
(continuous use by oral or infusion for more than 14 days) within 3 months, and
whole blood, plasma, or immunoglobulin within 1 month;

8. Known or suspected concomitant serious diseases, including: respiratory diseases,
acute infections or active chronic diseases, liver and kidney diseases, severe
diabetes, malignant tumours, infectious or allergic skin diseases, cardiovascular
disease, and HIV infection (with test report);

9. Subjects suffering from various acute diseases or in the acute exacerbation of
chronic diseases within 3 days before vaccination;

10. Subjects with clinically significant abnormalities in blood biochemistry, blood
routine, urine routine, coagulation function, thyroid function, and
myocarditis-related indicators detected during the screening;

11. Received live attenuated vaccine within 1 month before vaccination;

12. Received inactivated vaccine within 14 days before vaccination;

13. Axillary temperature ≥37.3℃;

14. Who have participated in other clinical trials within 3 months prior to the first
dose of vaccination or plan to participate in other clinical trials during the study
period;

15. Other conditions that the investigator deems inappropriate for participation in this
clinical trial.