1. Department of Biomedical and Clinical Sciences, Faculty of Medicine, Linköping University, Linköping, Sweden
2. Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway
3. Institute of Clinical Medicine, University of Oslo, Oslo, Norway
4. Landspitali University Hospital, Reykjavik, Iceland
5. University of Iceland, Reykjavik, Iceland
6. Division of Infectious Diseases, Helsinki University Hospital and Helsinki University, Helsinki, Finland
7. Statens Serum Institut, Copenhagen, Denmark
8. Odense University Hospital, Odense, Denmark