Primary TBE Vaccination for the Elderly

Primary TBE Vaccination for the Elderly

Tick-borne Encephalitis (TBE) can be prevented by vaccine. Vaccine failure, defined as a case of TBE regardless of previous vaccination, has been described and seems to be more predominant with increasing age, suggesting a less effective immune response following with increasing age. In fact previous studies has shown a reduced antibody response in elderly individuals compared to younger when vaccinated against TBE. As a result, in Sweden, an extra vaccine dose has been recommended during the primary vaccine schedule to individuals > 50 years of age. This alternative vaccine schedule has not been tested. The investigator aim to test if an extra vaccine dose in the primary vaccine schedule for those > 50 years of age improves the immune response and offers a corresponding immunity to younger individuals following TBE vaccination.

Inclusion Criteria:

• Adults ≥ 50 years or between 18-40 years
• Man or woman
• God health
• Written informed consent

Exclusion Criteria:

• Previous vaccination against TBE
• Previous TBE infection
• Allergy or hypersensitivity to any substance in the vaccine
• Previously known or suspected infection with Japanese encephalitis, Dengue virus, West Nile fever or Yellow fever
• Information on previous vaccination against Yellow fever or Japanese encephalitis
• Acute illness, eg fever with malaise
• Immunosuppression, due to medication or disease
• Previous treatment with Rituximab or equivalent
• Autoimmune disease, including diabetes (diet or tablet-treated diabetes with good metabolic control is accepted, HbA1c < 6 %)
• Obesity, BMI > 40
• Moderate to severe renal failure including hemodialysis, estimated GFR < 30.
• Blood transfusion or immunoglobulins <3 months ago
• Pregnancy
• Any other illness where the investigator consider the subject unsuitable for the study
• The study subject does not want to participate