Allison Kempe, MD, MPH¹, Matthew F. Daley, MD², Jennifer Pyrzanowski, MSPH¹, Tara Vogt³, Elizabeth Campagna, MS⁴, Hai Fang, PhD⁵, Deborah Rinehart, MA⁶, Nicole Morgan, MHA⁷, Mette Riis, BSN, MSW⁸, Sarah Rodgers, BA⁸, Emily McCormick, MPH⁸, Anne Hammer, BA, BSN, RN⁹, Simon Hambidge, MD, PhD¹⁰ and Judith Shlay, MD, MSPH⁸, 1Children's Outcomes Research Program, University of Colorado Denver, Aurora, CO, 2Institute for Health Research, Kaiser Permanente Colorado, Denver, CO, 3Immunization Services Division, NCIRD, CDC, Atlanta, GA, 4Colorado Health Outcomes Research, University of Colorado Denver, Aurora, CO, 5Department of Health Systems, Management and Policy, Colorado School of Public Health, University of Colorado Denver, Aurora, CO, 6Health Services Research, Denver Health, Denver, CO, 7Physician Billing, Denver Health, Denver, CO, 8Denver Public Health, Denver Health, Denver, CO, 9Denver Health Immunization Program, Denver Health, Denver, CO, 10Denver Community Health Services, Denver Health, Denver, CO