The phenomenon of no- and low-responsiveness has been described after applications of different vaccines (e.g. hepatitis B, TBE) and is concerning about 2-10% of the vaccinees.

The aim of this project is to investigate the humoral and cellular immune responses of low-responders after TBE vaccination in order to find parameters regarding immunoregulation against TBE. It is of interest if non-responsiveness is a general immunological deficit of a distinct patient group or if it is a antigen-specific phenomenon.

Inclusion Criteria:

• Adults (≥18 years) of both sexes without upper age limit
• Willingness to sign written informed consent form
• Basic vaccination plus one booster (minimum) of TBE-vaccine,

Exclusion Criteria:

• Age: < 18 years
• Pregnancy or breast feeding
• Prior TBE infection
• Planned surgery within 2 weeks before/after any scheduled rabies vaccination during the entire study
• Concomitant medication: systemic cortisone, immune suppressive therapy 4 weeks before or planned medication during the study
• History of autoimmune disease
• Drug addiction
• Plasma donators
• Administration of other vaccines 4 weeks before/after day 0
• Administration of immunoglobulins 6 weeks prior to any vaccination or blood donation during the entire study period
• Specific Immune Therapy (Hypo-/Desensibilization) within 14 days before and after the 2 study vaccination doses.
• History of any malignant disease 5 years prior to the study entry
• Any contraindication for the administration of the TBE- or influenza vaccine according to the manufactures information.