Evaluation of vaccination recall letter system for Medicaid-enrolled children aged 19-23 months--Montana, 2011

Abstract

Reminder and recall systems alert the parents of children due (reminder) or overdue (recall) for vaccination and have been associated with increased vaccination coverage. To evaluate the potential of a state-generated recall letter to increase vaccination coverage among Montana children, the Montana Department of Public Health and Human Services (DPHHS) pilot tested a recall letter system targeted at parents of children aged 19-23 months enrolled in Montana Medicaid and not known to have completed a subset of the routinely recommended vaccination series. Data extracted from Medicaid billing records and the web-based immunization registry database (WIZRD) then in use by Montana were used to ascertain whether children were up-to-date for the study vaccination series. Of the 1,865 children enrolled in Montana Medicaid and aged 19-23 months, 878 (47%) were eligible for study participation. One recall letter was sent to parents of 438 (50%) eligible children selected randomly. A reassessment of each child's vaccination status was completed 3 months after the initial mailing. At 3 months, 32% of children whose parents were sent letters were known to have completed the study vaccination series, which was not significantly different from the 28% of children who were vaccinated but whose parents had not been sent letters. Further research is needed to determine why the recall letter had limited effectiveness in this pilot study and to develop more effective methods for increasing vaccination coverage in Montana.