1. Department of Pediatric and Adult Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland.
2. Westat, Rockville, Maryland.
3. Department of Medicine, Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina.
4. Department of Pediatrics, Division of Allergy, Immunology, and Rheumatology, University of South Florida, St. Petersburg, Florida.
5. Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alabama.
6. Department of Pediatrics, New York University School of Medicine, New York, New York.
7. Pediatric, Adolescent, and Maternal AIDS Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.