1. Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles , CP160/12, 50 av. FD Roosevelt, Bruxelles 1050, Belgium
2. Department of Microbiology, Immunology and Transplantation, Laboratory of Clinical and Epidemiological Virology, Rega Institute, KU Leuven , Herestraat 49, Leuven 3000, Belgium
3. Department of Biostatistics, Fielding School of Public Health, and Departments of Biomathematics and Human Genetics, David Geffen School of Medicine, University of California Los Angeles , Los Angeles, CA 90095-1766, USA