This study is to assess the safety and immunogenicity of three consecutive lots of JE-CV in toddlers aged 12-18 months.

Primary objective:

To demonstrate the bio-equivalence of three lots of JE-CV vaccine manufactured by sanofi pasteur.

Secondary objective:

To describe the safety of vaccination in all subjects

This is a Phase III trial in toddlers in Thailand and the Philippines.

Inclusion Criteria :

• Aged 12 to 18 months on the day of inclusion.
• In good general health, without significant medical history.
• Provision of informed consent form signed by at least one parent or other legally acceptable representative, and by at least one independent witness if required by local regulations.
• Subject and parent/legally acceptable representative able to attend all scheduled visits and comply with all trial procedures.
• Completion of vaccinations according to the national immunization schedule.

Exclusion Criteria :

• Participation in another clinical trial investigating a vaccine, drug, medical device, or a medical procedure in the 4 weeks preceding the trial vaccination.
• Planned participation in another clinical trial during the present trial period.
• Known or suspected congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term systemic corticosteroids therapy.
• Known systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to a vaccine containing any of the same substances.
• Chronic illness at a stage that could interfere with trial conduct or completion, in the opinion of the Investigator.
• Receipt of blood or blood-derived products in the past 3 months, that might interfere with the assessment of the immune response.
• Administration of any anti-viral within 2 months preceding V01.
• History of central nervous system disorder or disease, including seizures.
• Personal or family history of thymic pathology (thymoma), thymectomy, or myasthenia.
• Receipt of any vaccine in the 4 weeks preceding the first trial vaccination.
• Planned receipt of any vaccine in the 4 weeks following any trial vaccination.
• Personal human immunodeficiency virus seropositivity in the blood sample taken at screening.
• Receipt of any JE vaccine or hepatitis A vaccine.
• Previous vaccination against flavivirus disease.
• History of flavivirus infection (confirmed either clinically, serologically or microbiologically)
• Thrombocytopenia, bleeding disorder or anticoagulants in the 3 weeks preceding inclusion contraindicating intramuscular vaccination.
• Febrile illness (temperature ≥38°C) or moderate or severe acute illness/infection on the day of vaccination, according to Investigator judgment.