1. Kaiser Permanente Colorado; Institute for Health Research; Denver CO USA
2. Colorado School of Public Health, Anschutz Medical Campus; Department of Epidemiology; Denver CO USA
3. Brigham and Women's Hospital and Harvard Medical School; Division of Pharmacoepidemiology and Pharmacoeconomics; Boston MA USA
4. University of Colorado Denver, School of Medicine; Department of Pediatrics; Denver CO USA
5. Kaiser Permanente Northern California, Division of Research; Vaccine Study Center; Oakland CA USA