1. Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
2. Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
3. Infectious Disease Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
4. Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, USA.
5. Department of Laboratory Medicine and Pathology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.