Kevin Dombkowski, DrPH, MS¹, Laura Harrington, MPH¹, Allison Kennedy, MPH², David Hanauer, MD³ and Sarah Clark, MPH¹, 1Child Health Evaluation and Research (CHEAR) Unit, Division of General Pediatrics, University of Michigan, Ann Arbor, MI, 2NCIRD/Immunization Services Division, CDC-NCIRD, Atlanta, GA, 3Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI