[1] University of the Free State,Centre for Health Systems Research & Development
[2] University of Antwerp,Department of Sociology and Research Centre for Longitudinal and Life Course Studies
[3] University of Alabama at Birmingham,Department of Health Behavior, School of Public Health
[4] State University of New York,Division of Infectious Diseases
[5] Downstate Medical Center,Department of Epidemiology
[6] State University of New York,undefined
[7] Downstate Medical Center,undefined