1. Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland;
2. Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, Maryland;
3. The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, Maryland;
4. Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland;
5. Department of Epidemiology, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska