Study of Japanese Encephalitis Chimeric Virus Vaccine (JE-CV) in Children Previously Immunized With JE-CV

An individual had to fulfill all of the following criteria in order to be eligible for trial enrollment:

All Participants

• Aged 36 to 42 months on the day of inclusion
• Provision of Informed Consent Form signed by at least one parent or other legally acceptable representative
• Participant and parent/legally acceptable representative or guardian able to attend all scheduled visits and to comply with all trial procedures
• In good general health, based on medical history and physical examination

For JE-CV vaccine primed group only

• Participant who was vaccinated with JE-CV in JEC02 trial (NCT00735644)

An individual fulfilling any of the following criteria was excluded from trial enrollment:

All Participants

• Participation in another clinical trial investigating a vaccine, drug, medical device, or medical procedure in the 4 weeks preceding the trial vaccination
• Planned participation in another clinical trial during the Day 0 - Month 6 period and for Group 1 up to 5 years for any flavivirus vaccine trial
• Receipt of any vaccine* in the 4 weeks preceding the trial vaccination, except for pandemic influenza vaccination, which may be received at least 2 weeks before study vaccines
• Planned receipt of any vaccine* in the 4 weeks following the trial vaccination, except for pandemic influenza vaccine. In the event of local or national immunization program with a pandemic influenza vaccine, participants who receive a pandemic influenza vaccine at any time during the trial will not be withdrawn from the trial.
• Planned receipt of any JE vaccine during the course of the trial
• Administration of any anti-viral within 2 months preceding the trial vaccination and up to 4 weeks following the trial vaccination
• Receipt of blood or blood-derived products in the past 3 months, which might interfere with assessment of the immune response
• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
• Seropositivity for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C, as reported by the parent/legally acceptable representative
• History of central nervous system disorder or disease, including seizures and febrile seizures
• Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccine used in the trial or to a vaccine containing any of the same substances
• Chronic illness or any underlying illness (such as cardiovascular, kidney, liver or hematological disease or development abnormalities) that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
• Except in case of national immunization days with oral polio vaccine

For JE-CV primed participants only

• Receipt of any JE vaccine other than JE-CV during JEC02 trial(NCT00735644) and since the end of JEC02 trial

For JE-CV naïve participants only

• Previous vaccination against flavivirus disease including JE
• History of flavivirus infection either based on clinical suspicion or laboratory proven
• Previous vaccination against varicella
• Previous vaccination with JE-CV in JEC02 study
• History of varicella, confirmed either clinically, serologically, or microbiologically
• Known systemic hypersensitivity or anaphylactic/anaphylactoid reaction to neomycin.
• Known history of thrombocytopenia or idiopathic thrombocytopenic purpura

Temporary Contraindications:

A prospective participant was not to be included in the study until the following conditions and/or symptoms had resolved:

• Receipt of oral or injected antibiotic therapy within 72 hours prior to the first blood draw (for Groups 1 and 2)
• Febrile illness (temperature ≥38.0°C [≥100.4°F]) or moderate or severe acute illness/infection (acc