1. Department of Occupational Medicine and Public Health, The Faroese Hospital System , Tórshavn , Faroe Islands
2. Centre of Health Sciences, University of the Faroe Islands , Tórshavn , Faroe Islands
3. Medical Department, National Hospital of the Faroe Islands , Tórshavn , Faroe Islands
4. Department of Infectious Diseases, Odense University Hospital , Odense , Denmark
5. Department of Clinical Research, University of Southern Denmark , Odense , Denmark
6. Department of Epidemiology Research, Statens Serum Institut , Copenhagen , Denmark