This phase III trial aims to assess the efficacy, safety and immunogenicity of SARS-CoV-2 Vaccine (inactivated) and lot-to-lot consistency evaluation

This trial is Randomized, observer-blind, placebo-controlled two arms parallel group, prospective intervention study

Approximately 1620 subjects aged 18-59 years will be enrolled in this trial for efficacy evaluation. Subjects will be divided into 2 treatment arms that are the vaccinated group and placebo group with ratio 1:1. The vaccinated arms will be grouped into three different lot number (lot 1/lot 2/ lot 3) of SARS-CoV-2 vaccine.

Inclusion Criteria:

1. Clinically healthy adults aged 18 - 59 years.
2. Subjects have been informed properly regarding the study and signed the informed consent form.
3. Subjects will commit to comply with the instructions of the investigator and the schedule of the trial.

Exclusion Criteria:

1. Subjects concomitantly enrolled or scheduled to be enrolled in another trial.
2. Contact with novel coronavirus infected persons (positive for nucleic acid detection) within 14 days prior to the trial.
3. Contact to patients with fever or respiratory symptoms surrounding areas or from communities with reported cases within 14 days prior to the trial.
4. Two or more cases of fever and/or respiratory symptoms in a small area such as home, office, school and class within 14 days prior to the trial.
5. Evolving mild, moderate or severe illness, especially infectious disease or fever (body temperature ≥37.5℃, measured with infrared thermometer/thermal gun).
6. The result of RT-PCR of swab nasopharyngeal is positive
7. Reactive IgG and IgM for SARS-CoV-2 (by standardize rapid test).
8. Women who are lactating, pregnant or planning to become pregnant during the study period (judged by self-report of subjects and urine pregnancy test results).
9. History of asthma, history of allergy to vaccines or vaccine ingredients, and severe adverse reactions to vaccines, such as urticaria, dyspnea, and angioneurotic edema.
10. History of uncontrolled coagulopathy or blood disorders contraindicating intramuscular injection.
11. Patients with serious chronic diseases (serious cardiovascular diseases, uncontrolled hypertension and diabetes, liver and kidney diseases, malignant tumors, etc) which according to the investigator might interfere with the assessment of the trial objectives.
12. Subjects who have any history of confirmed or suspected immunosuppressive or immunodeficient state, or received in the previous 4 weeks a treatment likely to alter the immune response (intravenous immunoglobulins, blood-derived products or long-term corticosteroid therapy (> 2 weeks)).
13. Subjects who have history of uncontrolled epilepsy or other progressive neurological disorders, such as Guillain-Barre Syndrome
14. Subjects receive any vaccination within 1 month before and after IP immunization.
15. Subjects plan to move from the study area before the end of study period.

Observer blind Investigational Product and Active Comparator was masking Number of lot was masking