immunogenicity and safety of chimerivax™ japanese encephalitis vaccine in thai toddlers and children

Conditions: Japanese Encephalitis; Hepatitis A

Summary: safety: to describe the safety profiles following vaccination. immunogenicity: to describe the immune response after a single dose of vaccine.

this is a randomized, cross-over, open, active controlled, multi-center trial in toddlers and children in thailand. stepwise enrollment of children in 2 age cohorts. subjects will be followed for 5 years.

Eligibility criteria:
inclusion criteria: * provision of consent form signed by at least one parent or another legally acceptable representative, and by at least one independent witness. * completion of vaccinations according to the national immunization schedule * subject and parent/legally acceptable representative able to attend all scheduled visits and comply with all trial procedures. * previous receipt of two doses of a mouse-brain-derived je vaccine at 12 to 15 months of age according to the national immunization schedule and aged 2 to 5 years on the day of inclusion. * aged 12 to 24 months on the day of inclusion and have not received any je vaccine. 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. * 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 the trial vaccine or 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. * receipt of hepatitis a vaccine. * history of flavivirus infection (confirmed either clinically, serologically or microbiologically). * administration of any anti-viral within 2 months preceding the screening visit. * history of central nervous system disorder or disease. * personal or family history of thymic pathology (thymoma), thymectomy, or myasthenia. * planned participation in another clinical trial during the present trial period. * 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, hepatitis b or hepatitis c seropositivity in the blood sample taken at screening. * thrombocytopenia, bleeding disorder or anticoagulants in the 3 weeks preceding inclusion contraindicating im vaccination. * previous vaccination against flavivirus disease at any time before the trial other than a mouse-brain-derived je vaccine given in a two-dose regimen at 12 to 15 months of age in accordance with the national immunization schedule. * febrile illness or any acute illness/infection on the day of vaccination, according to investigator judgment * history of seizures. * previous vaccination against flavivirus disease.

Keywords: japanese encephalitis (je) hepatitis a inactivated mouse-brain