1. HIV Vaccine Trials Network, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
2. Statistical Center for HIV/AIDS Research and Prevention, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
3. Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA.
4. Lausanne University Hospital and Swiss Vaccine Research Institute, Lausanne 1011, Switzerland.
5. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.