This study is a randomized, double-blinded, and placebo controlled phase Ⅱ clinical trial of the SARS-CoV-2 inactivated vaccine to evaluate the safety and immunogenicity of the experimental vaccine in healthy population aged 3 to 17 years.

Inclusion Criteria:

• Healthy residents aged 3 to 17 years at the time of consent
• Subjects and/or their guardian agree to sign the informed consent forms voluntarily.
• Be able to comply with study requirements/procedures.
• Axillary temperature ≤ 37.0℃

Exclusion Criteria:

• Within 14 days before vaccination, subjects have been abroad and to villages/communities experienced COVID-19 epidemics, and in contact with COVID-19 cases or suspected cases. Subjects are under isolation observation, or living in the villages/communities with COVID-19 cases or suspected cases;
• Confirmed cases, suspected cases or asymptomatic cases with COVID-19 (refer to Information System of China Disease Prevention and Control);
• Subjects with history of SARS virus infection by self-reported;
• Positive in throat swab through RT-PCR;
• History of vaccination of various COVID-19 vaccines or positive in SARS-CoV-2 antibody test;
• Positive urine pregnancy test for females with menarche
• History of severe allergic reactions (such as acute anaphylaxis, urticaria, skin eczema, dyspnea, angioneurotic edema or abdominal pain) or allergy to known composition of inactivated SARS-CoV-2 vaccine;
• History or family history of convulsion, epilepsy, encephalopathy or mental illness;
• Subjects with congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.;
• Subjects with known or suspected diseases include: severe respiratory diseases, severe cardiovascular diseases, severe liver and kidney diseases, drug-uncontrollable hypertension, diabetic complications, malignant tumors, various acute diseases or acute onset of chronic diseases;
• Diagnosed with congenital or acquired immunodeficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases;
• History of coagulation dysfunction (e.g. Coagulation factor deficiency, coagulation disease);
• Subjects receiving anti-TB treatment;
• Subjects receiving other research drugs within 6 months before vaccination;
• Subjects receiving immunotherapy or inhibitor therapy within 3 months (consistently oral or infusion for more than 14 days);
• Subjects receiving blood products within 3 months before administration;
• Subjects vaccinated with live attenuated vaccine within 14 days before vaccination;
• Subjects vaccinated with other vaccine within 7 days before vaccination;
• The researchers shall judge the other conditions which might be not in compliance with the requirements of this clinical trial.