Seroprevalence of Neutralizing Antibodies Against Japanese Encephalitis Virus Among 6 Years Old Children With 5 Different Immunization Strategies in Zhejiang Province

Inclusion Criteria: * Participants aged ≥ 72 months to \< 75 months. * Participants have completed routine immunization schedules in time. * Participants are healthy native residents. * Parents/guardians can understand the protocol requirements, provide informed consent, accept all scheduled visits, and comply with all trial procedures. Exclusion Criteria: * History of neurological diseases or related symptoms. * An acute illness with fever (temperature ≥ 37.1℃) or any acute onset of chronic diseases. * Known impairment of immunologic function, or receipt of immunosuppressive therapy or immunoglobulin in the past 3 months. * Known allergy to any constituent of the vaccine. * Have been injected with other vaccines or any clinical trial drugs in the past 4 weeks. * Any condition which, in the opinion of the investigator, would pose a health risk to the subject or interfere with the vaccine.