The goal of this clinical trial is to evaluate the efficacy, safety and immunogenicity of a live attenuated varicella vaccine manufactured by Beijing Institute of Biological Products Co., Ltd in healthy children.

This trial is aim to evaluate the efficacy, safety and immunogenicity of a live attenuated varicella vaccine manufactured by Beijing Institute of Biological Products Co., Ltd in healthy children aged 1-12 years old.

This study will be conducted in two stage. the stage 1 adopts an open design, and 20 subjects aged 18~59 and 13~17 years old (18~59 years old→ 13~17 years old, sequentially enrolled) are enrolled, and 1 dose of the trial vaccine is administered to explore safety.

The stage 2 adopts a randomized, blinded, placebo-controlled design, 12400 healthy participants aged 1-12 years old will be randomly assigned into experimental group or control group with the ratio 1:1.

Inclusion Criteria:

• Healthy volunteer between 13 - 59 years old for Stage 1, 1-12 years old for Stage 2, and be able to provide legal identification ;
• Subject and/or guardian has the ability to understand study requirements and processes, consent to participate in clinical trials, and sign informed consent forms;
• Consent to use effective contraception during study participation, no pregnancy and no family planning (for women of childbearing potential or their spouses);
• Axillary temperature ≤ 37.0 °C on the day of enrollment;

Exclusion Criteria:

• Has received any varicella vaccine before ( Not applicable to Stage 1）;
• Has history of varicella or herpes zoster infection, or contact with varicella/shingles patients or suspected varicella/shingles patients within 30 days before enrollment ( Not applicable to Stage 1）;
• Currently using salicylates (including salicylic acid, aspirin, diflunisalin, p-aminosalicylate (sodium), dicalicylate, benoxate, etc.), or plan to use it for a long time during the study；
• Have had febrile illness (axillary temperature ≥ 38.5 °C) or used antipyretic, analgesic, anti-allergic drugs (such as acetaminophen, ibuprofen, aspirin, loratadine, cetirizine, etc.) 3 days before vaccination；
• Have a history of allergy to vaccine components and excipients or severe drug allergy, such as anaphylactic shock, allergic laryngeal edema, Henoch-Schönlein purpura, thrombocytopenic purpura, local allergic necrosis (Arthus) reaction, severe urticaria, etc；
• Have a history of epilepsy, convulsions or convulsions, and have a family history of severe neurological disease or psychosis
• Immunocompromised or diagnosed with congenital or acquired immunodeficiency, HIV infection, lymphoma, leukemia, systemic lupus erythematosus, rheumatoid arthritis, juvenile rheumatoid arthritis, inflammatory bowel disease, or other autoimmune diseases；
• With severe congenital malformations, hereditary diseases, serious cardiovascular diseases, serious liver/kidney diseases, complicated diabetes, malignant tumors, and severe malnutrition
• Immunosuppressant therapy, such as long-term oral or injectable glucocorticoid therapy (≥ 14 days, dose ≥2 mg/kg/day or ≥20 mg/day or equivalent to prednisone), within 3 months prior to enrollment or planned within 30 days of vaccination, but topical medications (e.g., ointments, eye drops, inhalers, or nasal sprays) are not restricted
• Have received blood/blood-related products or immunoglobulins 3 months prior to vaccination, or plan to use such products 30 days after vaccination；
• Have received a live attenuated vaccine within 30 days prior to the trial vaccine, or any vaccine within 14 days prior to vaccination;
• Asplenectomy or splenectomy due to any condition (e.g. splenectomy);
• Those with a history of thrombocytopenia or other coagulation disorders, which may cause contraindications to subcutaneous injection;
• Suffering from various infectious, purulent or allergic skin diseases;
• Are participating in other investigational or unregistered clinical trials of products (drugs, vaccines or devices, etc.), or have plans to participate in other clinical trials before the end of this clinical trial;
• Has any other factors that are not suitable for participation in the clinical trial in the judgment of the investigator