1. Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.
2. for the Pediatric AIDS Clinical Trials Group (PACTG) 219/219C Study
3. Department of Preventive Medicine, Rush University, Chicago, Illinois.
4. Department of Biostatistics, Center for Biostatistics in AIDS Research (CBAR), Harvard School of Public Health, Boston, Massachusetts.