1. Department of Pediatrics University of Eastern Finland, Institute of Clinical Medicine Kuopio Finland
2. Department of Pediatrics Mikkeli Central Hospital Mikkeli Finland
3. Faculty of Social Sciences, Department of Epidemiology Tampere University Tampere Finland
4. Department of Infectious Diseases and Vaccinations Finnish Institute of Health and Welfare Tampere Finland
5. Department of Pediatrics Kuopio University Hospital Kuopio Finland
6. PEDEGO Research Unit University of Oulu Oulu Finland