Participation in the study will be offered to all participants of the cohort study "Evaluation of a vaccination campaign with A(H1N1)v pandemic vaccines: a prospective cohort study" AH1N1-483-09THL, who still live in the study area (city of Tampere) and who have complied to the SMS or phone follow-up. The eligibility criteria of the original study AH1N1-483-09THL were: full legal competence; community-dwelling; age 18 to 75 years, written informed consent obtained; able to communicate fluently in Finnish or Swedish and able to adhere to all protocol required study procedures without any special burden or risk. Originally, 3500 persons participated in the study