Objective: To evaluate immunogenicity and safety of a polygeline-free tick-born encephalitis (TBE) vaccine in a clinical program.
Method: A total of 3118 subjects aged 12-76 years were enrolled in three clinical trials. The clinical studies were conducted in 15 centers in three European countries. Evidence of neutralizing TBE antibodies was used as surrogate parameter for efficacy assessment.
Results: All subjects analyzed achieved levels of TBE antibodies postimmunization to fulfill the definition of seroconversion or a four-fold increase. The new TBE vaccine appeared to be well tolerated by subjects. Only very few febrile reactions, mainly 38.5 degrees C were reported. No serious or unexpected adverse events related to vaccination were reported.
Conclusion: These successful results in terms of both immunogenicity and safety indicate that the TBE vaccination with this polygeline-free TBE vaccine can be used safely in adolescents and adults.