open-label, randomized study in a pediatric population in a jev (japanese encephalitis virus)-endemic country

Conditions: Japanese Encephalitis

Summary: this is a randomized, open-label phase 3 study including children aged \>9 months to \<17 years and 7 months who have been vaccinated with ixiaro in study ic51-323.

this is a randomized, open-label phase 3 study including children aged \>9 months to \<17 years and 7 months who have been vaccinated with ixiaro in the previous study ic51-323.

Eligibility criteria:
inclusion criteria: * children and adolescents who have completed study ic51-323 and received both ixiaro vaccinations according to protocol. * children who have received the dose confirmed for their age group. * male or female healthy children and adolescents aged ≥9 months to \<17 years and 7 months at the time of enrolment into this study. * written informed consent by the subject's legal representative(s), according to local requirements, and written informed assent of the subject, if applicable. * female subjects: either no childbearing potential or negative pregnancy test (pregnancy test to be performed in female subjects after onset of menarche) at visits 1, 2 and 2a as stipulated by the protocol. for females after menarche willingness to practice a reliable method of contraception exclusion criteria: * vaccination against je virus (jev) (except within study ic51-323 and ic51 325), yellow fever, west nile virus and dengue fever at any time prior to or planned during the study. * history of or clinical manifestation of any flavivirus disease during ic51-323 or ic51 325. * participation in another study with an investigational drug during ic51 323 or ic51 325. * planned active or passive immunization within 2 weeks before and 1 week after the ixiaro booster. * history of or development of any immunodeficiency including post-organ-transplantation after inclusion into ic51-323 or ic51 325. * history of or development of an autoimmune disease during study ic51-323 or ic51 325. * administration of chronic (defined as more than 14 days) immunosuppressants or other immune-modifying medications started during ic51-323 or ic51 325. (for corticosteroids, this would mean prednisone or equivalent at \>0.05 mg/kg/day; topical and inhaled steroids are allowed). * acute febrile infection at visit 2 (only for the booster group). * pregnancy (positive pregnancy test at visit 1 and visit 2), lactation or unreliable contraception in female subjects after onset of menarche. * hypersensitivity reactions to ixiaro or adverse events in study ic51-323 requiring withdrawal from further vaccination or anaphylaxis or severe cases of atopy requiring emergency treatment or hospital admission during ic51-323 or ic51 325. * history of urticaria after hymenoptera envenomation, drugs, physical or other provocations or of idiopathic cause during ic51-323 or ic51 325. * known infection with human immunodeficiency virus (hiv), hepatitis b virus (hbv) (measurement of hepatitis b surface antigen \[hbsag\] titers) or hepatitis c virus (hcv). * illicit drug use and/or current drug or alcohol addiction. * inability or unwillingness by the legal representative(s) and/or the subject (where applicable) to provide informed consent/assent and to abide by the requirements of the study. * persons who have been committed to an institution (by a court or by an authority).

Keywords: immune response ic51-325 japanese encephalitis intercell ag