1. Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20205
2. Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201
3. University of Rochester School of Medicine, Rochester, New York 14627
4. Baylor College of Medicine, Houston, Texas 77000
5. Center for Disease Control, Atlanta, Georgia 30333
6. Department of Epidemiology, University of Michigan, School of Public Health, Ann Arbor, Michigan 43104