This study evaluates the immunogenicity and safety of a purified inactivated JE vaccine compared to a commercialized JE vaccine. In this phase III, randomized, blind trial, infants at 6-23 months of age were randomly assigned to three groups to receive experimental vaccine or control vaccine with two different vaccination schedule respectively.

The clinical study used randomized, blind method, commercialize inactivated Japanese encephalitis vaccine as control. In Infants at 6-23 months of age were injected with experimental vaccine with 0,7 days and 0,28 days vaccination schedule to evaluate immunogenicity and safety of the experimental vaccine and the effectiveness of different vaccination schedule. Participates were assigned to three groups (350 per group): group 1 with experimental vaccine using 0,7 days vaccination schedule; group 2 with control vaccine using 0, 7 days vaccination schedule; group 3 with experimental vaccine using 0, 28 vaccination schedule.

Blood samples were collected before immunization and 30 days after immunization, and the neutralization antibody of Japanese encephalitis was detected by plaque reduction neutralization test. Medical observation was conducted 30 minutes after each injection. Body temperature of participates was continuously measured for 7 days, and any adverse events were observed and recorded from the first dose to 30 days after the whole vaccination. Serious adverse events were collected within 6 months after the first dose.

Inclusion Criteria:

• 6-23 months old infants, no vaccination history of JE vaccine, no vaccination contraindication.
• informed consent of guardian / lawful written guardian, and signed informed consent;
• the guardian and family can comply with the requirements of the clinical trial scheme.
• there was no immunization history of immunoglobulins within three months, and there was no history of live vaccination within 14 days.
• the axillary temperature ≤ 37℃.

Exclusion Criteria:

• Allergy to any ingredient in the vaccine (any previous history of vaccine allergy); There are allergic, convulsive, epileptic, encephalopathy and psychiatric symptoms or signs.
• People with known or suspected (or high-risk) impairment or abnormality of immune function, such as those receiving immunosuppressive or immunopotentiator therapy, receiving blood products or plasma extracts within three months, or having an immunodeficiency virus infection or related disease in the mother or child.
• A history of thrombocytopenia or other coagulation disorders clearly diagnosed by the medical department, or a history of hemorrhagic constitution or prolonged bleeding time;
• Infected patients with known or suspected to have respiratory diseases, acute infections or active chronic diseases and are receiving antibiotic or antiviral treatment;
• In the past 3 days, fever (axillary body temperature≥38℃), oral or steroid hormones were given.
• Infectious or allergic skin diseases.
• Participating in another clinical researcher; or any situation that the researcher considers likely to affect the evaluation of the trial