This is a population-based prospective cohort study. Potential participants, males and females between 65 and 80 years of age, were selected randomly through the resident registration office in Hannover city, Germany and invited with a personalized letter to participate in the study.
Initially, a blood sample (40 ml) will be drawn from each participant (day 0). Furthermore, participants will be vaccinated against influenza with FLUAD 2014/2015. FLUAD is a trivalent, surface antigen, inactivated influenza virus vaccine adjuvanted with MF59C.1. Additional five blood samples will be collected during the study period of four months (at days 3, 7, 21, 70 and 130). Information about current and past infections, chronic diseases and basic sociodemographic data will be collected through a self-administered questionnaire.