1. Kaiser Permanente Vaccine Study Center, Kaiser Permanente Northern California, Oakland
2. Marshfield Clinic Research Institute, Marshfield, Wisconsin
3. HealthPartners Institute, Minneapolis, Minnesota
4. Center for Health Research, Kaiser Permanente Northwest, Portland, Oregon
5. Biostatistics Unit, Kaiser Permanente Washington Health Research Institute, Seattle, Washington
6. Research and Evaluation, Kaiser Permanente Southern California, Pasadena
7. Harvard Pilgrim Health Care Institute, Boston, Massachusetts
8. Institute for Health Research, Kaiser Permanente Colorado, Denver
9. Department of Epidemiology, Colorado School of Public Health, Aurora
10. Ambulatory Care Services, Denver Health, Denver, Colorado
11. University of Colorado School of Medicine, Aurora
12. Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, Georgia