1. Department of Epidemiology and Biostatistics Arnold School of Public Health, University of South Carolina 915 Greene Street, Columbia SC 29208 USA
2. Departments of Medicine and of Epidemiology and Biostatistics University of California San Francisco San Francisco CA USA
3. Division of Population Health National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention Atlanta GA USA
4. Saint Louis University College of Public Health and Social Justice Saint Louis MO USA
5. The Ohio State University Division of Epidemiology Columbus OH USA
6. Division of Adolescent and School Health National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA; US Public Health Service Commissioned Corps Rockville MD USA
7. Department of Epidemiology and Biostatistics Arnold School of Public Health, University of South Carolina 915 Greene Street Columbia SC 29208 USA