Inclusion Criteria:

1. Adults aged 18 years and older.

2. Understand the contents of the ICF and voluntarily sign it (If the participant is
unable to sign the ICF on his/her own due to illiteracy, an impartial witness is
needed).

3. Participants who are willing and able to comply with study requirements, including
all scheduled visits, vaccinations, laboratory tests, and other study procedures.

4. Female participants of childbearing potential or partners of male participants:
voluntarily agree to use effective contraception with their partners 14 days prior
to the vaccination and must agree to continue such precautions during the study
until 3 months after vaccination. [Effective contraception includes oral
contraceptives, injectable or implantable contraception, extended-release topical
contraceptives, hormonal patches, intrauterine devices (IUDs), sterilization,
abstinence, condoms (for males), diaphragms, cervical caps, etc.].

5. For female participants: without childbearing potential (amenorrhea for at least 1
year or documented surgical sterilization) or have used effective contraception with
a negative pregnancy test before vaccination in this study.

6. Axillary temperature <37.3°C/99.1°F at screening visit and 72 hours prior to
vaccination.

7. Healthy participants or participants with mild underlying disease [in a stable state
without exacerbation (no admission to hospital or no major adjustment to treatment
regimen, etc.) for at least 3 months prior to enrollment in this study].

8. Participants who have vaccinated 2 doses of CoronaVac® (with an interval of 3-8
weeks between 2 doses), for 6-12 months prior to enrollment.

Exclusion Criteria:

1. Previous medications intervention for the prophylaxis or prevention of COVID-19
(Including vaccination with any licensed SARS-CoV-2 vaccines other than 2 doses of
CoronaVac® ).

2. History of Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory
Syndrome (MERS) or other coronavirus infections.

3. History of a previous laboratory-confirmed diagnosis of SARS-CoV-2 infection or
COVID-19.

4. History of allergy to any component of the study vaccine or history of severe
allergic reaction to the vaccine or drug (including but not limited to anaphylaxis,
allergic laryngeal oedema, anaphylactic purpura, thrombocytopenic purpura, or
localized allergic necrosis (Arthus reaction)).

5. Positive nucleic acid for SARS-CoV-2 in nasopharyngeal/oropharyngeal swab specimens.

6. Positive HIV test result.

7. A history or family history of convulsions, epilepsy, encephalopathy and psychosis.

8. Malignant tumors in the active phase, malignant tumors not receiving adequate
treatment, malignant tumors at potential risk of recurrence during the study period.

9. Congenital or functional splenic deficiency, complete or partial splenectomy for any
reason.

10. Prolonged (defined as more than 14 days) use of immunosuppressive or other
immunomodulatory drugs (e.g., corticosteroids, ≥20 mg/d prednisone or equivalent;
however, inhaled and topical steroids are permitted) within 6 months prior to the
vaccine.

11. Any other licensed vaccines given within 28 days prior to the study vaccination, or
planned administration of vaccine(s) within 28 days after vaccination.

12. Have received immunoglobulin or other blood products within 3 months prior to
enrollment or plan to receive them during the study period.

13. Blood donation or blood loss ≥ 450 mL within 1 month prior to enrolment, or planned
donation during the study period.

14. Participants who have received any other investigational product within 1 month
prior to enrollment or intent to participate in another clinical study at any time
during the conduct of this study.

15. Female participants who are pregnant or breastfeeding.

16. Participants deemed unsuitable for participation in this study based on the
investigator's assessment.