1. Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
2. Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
3. Department of Infectious Diseases, Robert Koch-Institute, Wernigerode, Germany
4. Department of Infectious Disease Epidemiology, Robert Koch-Institute, Berlin, Germany
5. Department of Internal Medicine III, RWTH Aachen University Hospital, Aachen, Germany