1. Cochrane Haematology, Department I of Internal Medicine, Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf; Faculty of Medicine and University Hospital Cologne, University of Cologne; Cologne Germany
2. Laboratory of Experimental Immunology, Institute of Virology; Faculty of Medicine and University Hospital Cologne, University of Cologne; Cologne Germany
3. Department of Epidemiology; Helmholtz Centre for Infection Research; Braunschweig Germany
4. Cochrane Cancer, Department I of Internal Medicine, Center for Integrated Oncology Aachen Bonn Cologne Duesseldorf; Faculty of Medicine and University Hospital Cologne, University of Cologne; Cologne Germany