1. Department of Pediatrics and Adolescent Medicine, Turku University Hospital and University of Turku , Turku , Finland
2. Virology Unit, Institute of Biomedicine, University of Turku , Turku , Finland
3. Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen , Copenhagen , Denmark
4. Research Unit for Pediatrics, Dermatology, Clinical Genetics, Obstetrics and Gynecology, University of Oulu , Oulu , Finland
5. Department of Pediatrics and Adolescent Medicine, University of Oulu , Oulu , Finland