Influence of Persistent CMV-infection on Immune Senescence

Inclusion criteria: * Age \> 70 years * Healthy according to a health questionnaire (completed before screening) * TBE-Vaccination indicated (exposure to TBEV-infested ticks possible) * Capable to make an informed decision and to understand the informed consent form * Informed consent signed by patient and study physician Exclusion criteria: * Previous exposure to TBEV (natural or vaccination) * Immunodeficiency, history of autoimmune disease or current intake of immune-modulating drugs (corticosteroids a.s.o.) * Persistent (\> 3 months) pharmacological treatment with more than one drug of relevance (exception: combination antihypertensives) * Contraindication for TBEV-vaccination * Condition that would drastically interfere with clinic attendance and/or adherence to the protocol * Past medical history or current treatment for one of the following conditions: Chronic cardiac disease (Coronary heart disease, heart failure), chronic pulmonary disease (COPD), chronic kidney disease, diabetes mellitus, previous stroke, epilepsy, Parkinsons disease, dementia * Hemoglobin \<12 g/l * Random plasma glucose (RPG) \> 11.1 mmol/l OR fasting plasma glucose (FPG) \> 6.9 mmol/l (FPG required, if RPG is 7.0-11.0 mmol/l) * Calculated Creatinin-Clearance \< 50 ml/min * TBEV-serology positive