1. a UNC-Chapel Hill School of Public Health, Department of Epidemiology , Chapel Hill, North Carolina, USA
2. b UNC-Chapel Hill School of Public Health, Department of Health Education and Health Behavior , Chapel Hill, North Carolina, USA
3. c UNC-Chapel Hill School of Public Health, Department of Epidemiology, UNC-Chapel Hill School of Medicine, Department of Infectious Diseases , Chapel Hill, North Carolina
4. d North Carolina Department of Health and Human Services , Raleigh, North Carolina, USA