A Study of Japanese Encephalitis Chimeric Virus Vaccine Compared With SA14-14-2 Vaccine in Infants and Toddlers

The purpose of this study is to compare a single dose of Japanese encephalitis (JE) chimeric virus vaccine (JE-CV) with a single dose of SA14-14-2 live vaccine as primary vaccination in infants and toddlers.

Primary Objective:

* To demonstrate the non-inferiority of the antibody response 28 days after vaccine administration of one dose of JE CV (administered on Day 0) compared to the antibody response after one dose of the SA14-14-2 control vaccine (administered on Day 0).

Secondary Objectives:

* To describe the immune response to JE in both vaccine groups in JE-CV virus and SA14-14-2 virus before and after a single dose of JE CV or a single dose of SA14-14-2 vaccine
* To describe the safety profile in all vaccinated subjects up to 28 days and all serious adverse events (SAEs) up to 6 months after vaccination.
* To describe only related SAEs and all death from 6 month to 12-month follow-up.

All participants will receive one injection of their randomized vaccine on Day 0. Follow-up will continue for 12 months after vaccination.

Eligibility Criteria:
Inclusion Criteria :

* Aged 9 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 representatives 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 first 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 corticosteroid 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
* Previous vaccination against flavivirus disease, including Japanese encephalitis (JE)
* Administration of any anti-viral within 2 months preceding first vaccination and up to the 4 weeks following the last trial vaccination at Month 3
* Receipt of any vaccine in the 4 weeks preceding the first trial vaccination
* Planned receipt of any vaccine from the inclusion up to the 4 weeks following the last trial vaccination
* Planned receipt of any Japanese encephalitis vaccine during the course of the study
* History of central nervous system disorder or disease, including seizures
* History of flavivirus infection (confirmed either clinically, serologically or microbiologically)
* Febrile illness (temperature ≥ 38°C) or moderate or severe acute illness/infection on the day of vaccination, according to Investigator judgment.