1 Department of Clinical Immunology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
2 Helsinki University Ctrl. Hospital, Helsinki, Finland.
3 Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
4 Laboratory Medicine Program, University Health Network and University of Toronto, Toronto, ON, Canada.
5 Department of Pathology, University Hospital of Oslo, Oslo, Norway.
6 Department of Clinical Chemistry and Laboratory Division, University of Turku and Turku University Hospital, Turku, Finland.
7 Department of Immunology, Oslo University Hospital Rikshospitalet, Oslo, Norway.
8 Department of Pathology, Laboratory of Molecular Pathology, Oslo University Hospital, Oslo, Norway.
9 Department of Medical Biosciences, Pathology, Umeå University, Umeå, Sweden.
10 Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
11 Department of Physiology, Biochemistry, Microbiology and Laboratory Medicine, Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
12 Centre of Laboratory Medicine, Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania.
13 Hematology, Oncology and Transfusion Medicine Centre, Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania.
14 Department of Clinical Chemistry, Sahlgrenska University Hospital, and Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
15 Department of Clinical Immunology, North Estonia Medical Centre, Tallinn, Estonia.
16 Department of Hematology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
17 Children's Hospital, Landspitali University Hospital, Reykjavik, Iceland.
18 Tallinn Children's Hospital, Tallinn, Estonia.
19 Children's Hospital, Affiliate of Vilnius University Hospital Santariskiu Klinikos, Vilnius, Lithuania.
20 Department of Pediatrics, Helsinki University Children's Hospital and University of Helsinki, Helsinki, Finland.
21 Department of Pediatrics, St. Olavs University Hospital and Department of Clinical and Molecular Medicine, NTNU, Trondheim, Norway.
22 Institution of Clinical Sciences, Department of Pediatrics, Sahlgrenska University Hospital, Gothenburg, Sweden.
23 Department of Pediatrics and Adolescent Medicine, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
24 The Institute of Clinical medicine, The Faculty of Medicine, University of Copenhagen, Copenhagen, Denmark.
25 Department of Clinical Immunology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark. hanne.marquart@regionh.dk.