6-year Antibody Check After Third Vaccination Against Japanese Encephalitis

Neutralizing Antibody Titers 6 Years After the Third Dose of Inactivated Japanese Encephalitis Vaccine and Projected Duration of Protection

The purpose of this study is to determine whether there are persisting antibodies against Japanese Encephalitis 6 years after the last vaccination with IXIARO(R) and to adapt or confirm mathematical models accordingly.

Japanese Encephalitis (JE) is a potentially devastating mosquito-borne viral disease. The JE virus (JEV), a Flavivirus, is endemic to many regions in Asia, and while JE is primarily a pediatric disease in the endemic regions, travelers from non-endemic regions to Asia are usually naïve to the virus and may be at risk for contracting JE at any age.

The present study aims to investigate antibody titers at approximately 6 years after the third dose of JE vaccine (JE-VC), in a cohort of participants from an earlier booster dose trial, to strengthen the statistical model of the duration of protection after the booster.

Inclusion Criteria:

• Subjects who received a booster dose of JE-VC in study IC51-311
• Subjects who are willing to give written informed consent to participate in the trial

Exclusion Criteria:

• Subjects who received a further dose of any Japanese Encephalitis Vaccine since study IC51-311
• Severe immunosuppression (as result of medical conditions or medication) since study IC51-311, such as history of radiation therapy or cytostatic therapy
• simultaneous participation in another clinical study