1. Immunization Safety Office; Centers for Disease Control and Prevention; Atlanta GA USA
2. Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine; Harvard Medical School and Brigham and Women's Hospital; Boston MA USA
3. Kaiser Permanente Vaccine Study Center; Oakland CA USA
4. Group Health Research Institute and University of Washington; Seattle WA USA
5. Institute for Health Research, Kaiser Permanente; Denver CO USA
6. Southern California Kaiser Permanente; Pasadena CA USA