1. Department of Infectious Diseases Faculty of Medicine and Health School of Medical Sciences Örebro University Örebro Sweden
2. Department of Infectious Diseases Karolinska Institutet Stockholm Sweden
3. Department of Gastroenterology and Hepatology Karolinska Institutet Stockholm Sweden
4. Clinical Epidemiology and Biostatistics School of Medical Sciences Örebro University Örebro Sweden
5. Clinical Epidemiology Division Karolinska Institutet Stockholm Sweden
6. Department of Epidemiology and Public Health University College London London UK
7. Scandinavian Development Services Stockholm Sweden