Edouard Vannier1, Peter J Krause2. 1. Department of Medicine, Tufts Medical Center and Tufts University School of Medicine, Boston, MA. 2. Department of Epidemiology of Microbial Diseases, Yale School of Public Health and Departments of Medicine and Pediatrics, Yale School of Medicine, 60 College Street, New Haven, CT 06520, USA. Electronic address: peter.krause@yale.edu.