1. Department of Medicine Huddinge, Karolinska Institutet, Stockholm
2. Centre for Clinical Research Västmanland, Västmanland County Hospital, Uppsala University, Västerås
3. Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg
4. Department of Infectious Diseases, Karolinska University Hospital
5. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.