1. Department of Epidemiology, University of North Carolina, Chapel Hill;
2. Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia;
3. Department of Medicine, University of California, San Diego;
4. Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland;
5. Department of Medicine, University of Washington, Seattle;
6. Department of Medicine, University of Alabama at Birmingham; and
7. Department of Medicine, University of North Carolina, Chapel Hill