A Study to Evaluate The Efficacy, Safety and Immunogenicity of Inactivated SARS-CoV-2 Vaccines (Vero Cell) in Healthy Population Aged 18 Years Old and Above

This is a multicenter, randomized, double-blind, placebo-controlled study to evaluate the protective efficacy, safety and immunogenicity of inactivated SARS-CoV-2 vaccines in healthy population 18 years old and above. The participants were randomized into three groups of investigational vaccine 1, investigational vaccine 2 and placebo in a 1:1:1 ratio.2 doses of the investigational vaccine or placebo are inoculated into the deltoid muscle of the either arm according to the vaccination schedule of D0 & D21 (+7 days).According to the immune durability results in Phase I/II study, and cross-neutralization assay results, a third dose (booster dose) generates a better immune response and is estimated to offer better protection, therefore, a booster dose will be given after 3 months

Inclusion criteria

• Healthy subjects aged 18 years old and above.
• By asking for medical history and physical examination, the investigator judged that the health condition is well.
• Female subjects of childbearing age are not nursing or pregnant at the time of enrolment (negative urine pregnancy test) and have no family planning within the first 3 months after enrolment. Effective contraceptive measures have been taken within 2 weeks before inclusion.
• During the whole follow-up period of the study, be able and willing to complete the whole prescribed study plan.
• With self-ability to understand the study procedures, the informed consent & voluntarily sign an informed consent form and be able to comply with the requirements of the clinical study protocol.

Exclusion criteria

• Confirmed acute cases of SARS-CoV-2 Infection.
• Have a history of SARS, MERS infection (self-report, on-site inquiry).
• Positive urine pregnancy test result.
• Fever (body temperature > 37.0 ℃), dry cough, fatigue, nasal obstruction, runny nose, pharyngeal pain, myalgia, diarrhea, shortness of breath and dyspnea occurred within 14 days before vaccination.
• Axillary body temperature > 37.0 ℃ before vaccination.
• Previous severe allergic reactions to vaccination (such as acute allergic reactions, urticaria, dyspnea, angioneurotic edema or abdominal pain) or allergy to known ingredients of inactivated SARS-CoV-2 vaccine have occurred.
• Has a history of convulsion, epilepsy, encephalopathy or mental illness or family history.
• With congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.
• With severe liver diseases, severe kidney diseases defined as eGFR less than 60, uncontrollable hypertension (systolic blood pressure >150 mmHg, diastolic blood pressure > 90 mmHg), diabetic complications, malignant tumors, various acute diseases, or acute attack period of chronic diseases.
• Has been diagnosed with congenital or acquired immune deficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases.
• With known or suspected diseases include acute respiratory diseases (e.g. influenza like illness, acute cough, sore throat), severe cardiovascular diseases, liver and kidney diseases, and malignant tumors.
• Has a history of coagulation dysfunction (e.g. Coagulation factor deficiency, coagulation disease).
• Receiving anti-TB therapy.
• Patients receiving immunotherapy or inhibitor therapy within 3 months (continuous oral or infusion for more than 14 days).
• Live attenuated vaccine is inoculated within 1 month before this vaccination, other vaccines are inoculated within 14 days before this vaccination.
• Received blood products within 3 months before this vaccination
• Received other research drugs within 6 months before this vaccination.
• Other circumstances judged by investigators that are not suitable for this clinical trial.