Study of a Live Attenuated Japanese Encephalitis Chimeric Virus Vaccine (IMOJEV™) Compared to CD.JEVAX™ in Toddlers

Immunogenicity and Safety of a Single Dose of a Live Attenuated Japanese Encephalitis Chimeric Virus Vaccine (IMOJEV™) in Comparison With a Single Dose of SA14-14-2 Vaccine (CD.JEVAX™, Chengdu Institute of Biological Products, China) Administered in Healthy Toddlers in South-Korea

The purpose of this study is to compare Live Attenuated Japanese Encephalitis Chimeric Virus Vaccine (IMOJEV™) with Japanese encephalitis live attenuated vaccine (SA14 14 2 vaccine [CD.JEVAX™]) after a single dose vaccination to support product registration.

Primary Objective:

• To demonstrate the non-inferiority of the antibody response 28 days after administration of one dose of IMOJEV™ compared to the antibody response 28 days after administration of one dose of the CD.JEVAX™ control vaccine.

Secondary Objectives:

• To describe the immune response to Japanese encephalitis (JE) in both vaccine groups using 50% plaque reduction neutralization assay (PRNT50) assays before and after a single dose of IMOJEV™ vaccine or a single dose of CD.JEVAX™ vaccine.
• To describe the safety of vaccination in all subjects up to 28 days and all serious adverse events up to 6-month after vaccination.

All participants will receive a single dose of their assigned vaccination at Visit 1 (Day 0) and undergo immunogenicity assessment at Day 28 post-vaccination. Safety will be assessed from day of vaccination and up to 6 months post-vaccination.

Inclusion Criteria:

• Aged 12 to 24 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.
• Subject and parent/guardian able to attend all scheduled visits and comply with all trial procedures.

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, or receipt of 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 IMOJEV™ components or history of a life-threatening reaction to a vaccine containing any of the same substances and vaccination,known systemic hypersensitivity to CD.JEVAX® main components and the other components (including Gelatin, kanamycin, and gentamicin).
• 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 Visit 01 and up to the 4 weeks following the trial vaccination.
• Receipt of any vaccine in the 4 weeks preceding the first trial vaccination, except for pandemic influenza vaccination, which may be received at least two weeks before the study vaccines.
• Planned receipt of any vaccine from the inclusion up to the 4 weeks following the trial vaccination.
• History of central nervous system disorder or disease, including seizures.
• Planned receipt of any JE vaccine during the course of the study.
• History of flavivirus infection (confirmed either clinically, serologically or virologically).
• Administration of systemic corticosteroids for more than two consecutive weeks within the 4 weeks preceding vaccination.
• Febrile illness (temperature ≥38.0°C) or moderate or severe acute illness/infection 3 days before vaccination as well as the day of vaccination, according to Investigator judgment.
• Thrombocytopenia or bleeding disorder contraindicated for vaccination with same administration route, or receipt of anticoagulants in the 3 weeks preceding inclusion.