1. Institute of Medical Biometry, Informatics and Epidemiology; University of Bonn; Sigmund-Freud-Str. 25 Bonn 53127 Germany
2. Department of Statistics; University of Munich; Ludwigstr. 33 Munich 80539 Germany
3. Institute of Medical Microbiology, Immunology and Parasitology; University of Bonn; Sigmund-Freud-Str. 25 Bonn 53127 Germany
4. German Center for Infection Research (DZIF), Partner Site Bonn-Cologne; Bonn 53127 Germany