1. Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
2. Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
3. Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA.
4. Department of Biostatistics, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, MA 02115, USA.
5. School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, Ireland.
6. Department of Statistical Sciences, University of Cape Town, Cape Town, South Africa.
7. Blood Systems Research Institute, University of California, San Francisco, CA 94118, USA.
8. Department of Biostatistics, School of Public Health, University of North Carolina, Chapel Hill, NC 27599, USA.
9. Vaccine Infectious Disease Institute, Fred Hutchinson Cancer Research Center and Department of Biostatistics, University of Washington, Seattle, WA 98109, USA.
10. Department of Medicine, University of Alabama, Birmingham, AL 35233, USA.
11. BioQual Inc., Rockville, MD 20850, USA.