A multi-center, open, phase 4 clinical trial to assess the long-term immunogenicity and safety of fourth administration of Boryung Cell-Culture Japanese Encephalitis Vaccine inj. and to conduct an exploratory investigation on vaccine interchangeability in Korean children aged 6 years who received primary 3 doses with ENCEVAC® or Japanese Encephalitis Vaccine-GCC® inj.

This is a follow-up study of KD287-BR-CT-301 (ClinicalTrials.gov identifier: NCT01150942), a phase 3 study to investigate the efficacy and safety of a cell-culture Japanese encephalitis vaccine (ENCEVAC®) compared with that of a mouse brain-derived Japanese encephalitis vaccine (Japanese Encephalitis vaccine-GCC® inj). Subjects participated in KD287-BR-CT-301 study were to receive 3 doses of Japanese encephalitis vaccine (JEV) assigned by randomization from the age of 12 months and those subjects who completed the 3 doses of JEV are the target population in this study. The purpose of this study is to investigate the long-term immunogenicity and safety of the booster (fourth) dose of JEV, which will be given as Boryung Cell-Culture Japanese Encephalitis Vaccine inj, proven to be same with ENCEVAC® but manufactured by a different manufacturer.

Inclusion Criteria:

• Parent/guardian (legally authorized representative) has given voluntary written consent to the subject's participation after being fully informed of the purpose, methods, risks, and benefits of the study.
• Male and female children who have completed the primary 3 doses of JEV in the KD287-BR-CT-301study.
• Male and female children reaching at least 6 years of age on the day of booster dosing of JEV.
• Male and female children who are identified to be healthy based on physical examination and medical history.

Exclusion Criteria:

• Children who have acute febrile illness with tympanic temperature of ≥38.0 ℃ on the day of booster dosing of JEV.
• Children who have moderate or severe acute disease (regardless of fever).
• Children who have history of encephalitis, encephalopathy, cerebromeningitis, or convulsion.
• Children who have received JEV (including live JEV) other than the investigational products administered in the KD287-BR-CT-301study.
• Children who have had fever (≥ 40 °C) or systemic allergy within 48 hours after vaccination.
• Children who have shown anaphylactic reaction to the investigational products administered in the KD287-BR-CT-301study or who are likely to be allergic to the ingredients of the investigational product.
• Children who have been diagnosed with immunodeficiency such as acquired immune deficiency or who have family history of immunodeficiency.
• Children who have received other vaccines within 28 days before booster dosing of JEV (vaccines to be administered according to the national vaccination program.
• Children who have received immunosuppressive thera-py within 28 days before booster dosing of JEV.
• There is a possibility that immune globulin preparations has not been excreted enough on the day of booster dosing of JEV if children have received such a product.
• Children who are currently participating or planning to participate in other clinical stud-ies during the study period.
• Other ineligible conditions judged at the discretion of principal investigators or subinvestigators.

Open Label