Study on Booster Immunization With Varicella Vaccine at Different Intervals

Inclusion Criteria: * Healthy children aged 7-12 years; * Has previously received a single dose of varicella vaccine, with at least 3 months since the first dose; * The subject or legal guardian can understand and sign the informed consent form (double signature is required for those over 8 years old); * Participants and their legal guardians voluntarily participate in the study and are able to comply with all study procedures; * Provide legal identity proof; Exclusion Criteria: * History of varicella; * History of severe allergic reactions to vaccines (such as acute anaphylaxis, angioedema, dyspnea, etc.); * Suffering from acute disease, severe chronic disease, acute exacerbation of chronic disease; * With any confirmed or suspected immunodeficiency disease, immunocompromised or receiving immunosuppressive therapy (including systemic steroid therapy); * With a history of congenital immune diseases or close contact with family members with a history of congenital immune diseases; * With encephalopathy, uncontrolled epilepsy, other progressive neurological disorders, history of Guillain-Barre syndrome; * Body temperature \>37℃ at the time of vaccination; * Receipt of blood products within 3 months before receiving investigational vaccine; * Receipt of another study drug within 30 days before receipt of the investigational vaccine; * Receipt of live attenuated vaccine within 28 days before receipt of investigational vaccine; * Receipt of subunit or inactivated vaccine within 7 days before receipt of investigational vaccine; * Participated in other clinical trials before enrollment and were enrolled in another clinical trial during the follow-up period or planned to participate in another clinical trial within 3 months; * The participant had any other factors that were ineligible for vaccination by in the investigator's judgment.