Allergic patients especially those undergoing de-sensitization treatment have an altered immune responsiveness. The investigators aim to find out whether this influences immune responses to primary and booster vaccinations.

Allergic patients generally have an altered immunologic profile (Th2 bias), and allergic individuals undergoing de-sensitization treatment display an increased production of immune suppressive cytokines. The investigators measure humoral and cellular immune responses to routine vaccination (Tick-borne Encephalitis [TBE] booster) in allergic patients with and without de-sensitization treatment to determine whether allergy negatively influences vaccine induced immune responses and protection.

Inclusion Criteria:

• completed primary TBE immunization + at least one booster immunization
• adults of both sexes between 18 and 60 years of age
• willingness to sign written informed consent form

Exclusion Criteria:

• age < 18 and > 60 years
• prior TBE infection
• Hepatitis A vaccination
• pregnancy and breast feeding
• acute infection on day of inclusion (day 0), body temperature >37,9°C
• concomitant medications: systemic cortisone therapy, chemotherapy, immunosuppressive therapy 4 weeks prior to or during study
• administration of other vaccines 4 weeks before/after TBE vaccination
• planned surgery within 2 weeks before/after TBE vaccination
• Start of de-sensitization and the first 4 weeks of allergen dose escalation
• any contraindication to administration of FSME-Immun® vaccine according to manufacturer's instructions
• history of malignant disease within the last 5 years
• autoimmune diseases
• drug addictions
• plasma donors
• receipt of blood transfusions or immuno globulins within 3 month before study entry