Long Term Persistence and Effect of a Booster Dose of the Japanese Encephalitis Vaccine IC51
Japanese Encephalitis
About this trial
This is an interventional prevention trial for Japanese Encephalitis
Eligibility Criteria
Inclusion Criteria:
- At least 18 years of age
- Written informed consent obtained prior to study entry
- Subjects correctly included in and having completed study IC51-304 according to the protocol.
Exclusion Criteria:
- Use of any other investigational or non-registered drug or vaccine in addition to the study vaccine during the study period
- Immunodeficiency including post-organ-transplantation or immunosuppressive therapy
- Pregnancy, lactation or unreliable contraception in female subjects
Sites / Locations
Arms of the Study
Arm 1
Other
IC51
In study IC51-305, subjects who had received IC51 in study IC51-304 were tested for seroconversion 6 months after the first vaccination. Subjects who had protective titers were again tested for persistence of immunity at 12 months after the first immunization,whereas subjects who had titers below the seroconversion threshold by Month 6 received a booster dose of 1x6 mcg IC51 at Month 11. Their immune response was also assessed at Month 12. Thereafter, subjects who had no protective titer by Month 12 received a booster dose of 1x6 mcg IC51 at Month 23, regardless of prior treatment; and neutralizing antibody titers were reassessed at Month 24. Subjects who had protective titers at month 12 did not receive a booster at Month 23, and their neutralizing antibody titer was also assessed at Month 24.