1. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;
2. Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark;
3. Department of Clinical Immunology, Aalborg University Hospital, Aalborg, Denmark;
4. Department of Clinical Immunology, Odense University Hospital, Odense, Denmark;
5. Department of Hematology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark; and
6. Hematology Centre, Karolinska University Hospital, Stockholm, Sweden