1. Department of Community Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway;
2. Innlandet Hospital Trust, Gjøvik, Norway;
3. The Norwegian Centre for Addiction Research, Faculty of Medicine, University of Oslo, Oslo, Norway;
4. Department of Infectious Diseases, Oslo University Hospital, Oslo, Norway;
5. Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway