1. Department of Health Behavior, Gillings School of Global Public Health, University of North Carolina, 135 Dauer Drive Chapel Hill, NC 27599-7400, USA
2. Department of Maternal and Child Health, Gillings School of Global Public Health, University of North Carolina, 135 Dauer Drive Chapel Hill, NC 27599-7400, USA
3. HIV Central America Regional Program, Center for Health Studies, Universidad del Valle de Guatemala, 18 Avenida 11-95, Zona 15, Vista Hermosa III, Guatemala City, Guatemala
4. US Center for Disease Control and Prevention (CDC) Central America Region, 11 calle 15-79, Zona 15, Vista Hermosa III, Guatemala City, Guatemala