Affiliation: | a Department of Nursing Science, 20014 University of Turku, Turku, Finlandb Department of Vaccines and Immune Protection, National Institute for Health and Welfare, Helsinki and University of Tampere, Tampere, 00300 Helsinki, Finlandc Population Studies Unit, National Institute for Health and Welfare, Turku, 20720 Turku, Finlandd Department of Nursing Science and Hospital District of South-West Finland, Turku 20014 University of Turku, Turku, Finland |