1. Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark;
2. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;
3. Department of Clinical Immunology, Blood Bank, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark;
4. Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark;
5. Department of Clinical Immunology, Naestved Hospital, Naestved, Denmark;
6. Department of Clinical Immunology, Aalborg University Hospital, Aalborg, Denmark;
7. South Danish Transfusion Service/Department of Clinical Immunology, Odense University Hospital, Odense, Denmark; and
8. Hematology Centre, Karolinska University Hospital, Stockholm, Sweden