1. Institute for Experimental Immunology, University of Zurich, Zurich, Switzerland
2. Epidemiology, Biostatistics and Prevention Institute, Department of Public and Global Health, University of Zurich, Zurich, Switzerland
3. Communicable Diseases Division, Swiss Federal Office of Public Health (FOPH), Bern, Switzerland
4. Epidemiology, Biostatistics and Prevention Institute, Department of Epidemiology, University of Zurich, Zurich, Switzerland