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