1 aDepartment of Infectious Disease, Geffen School of Medicine bDepartment of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, California cVanderbilt Institute for Global Health and Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA dSchool of Public Health, University of Nairobi, Kenya eNational Health Laboratory Service, Durban, South Africa.