Changes in childhood immunization disparities between central cities and their respective states, 2000 versus 2006

Central cities have lower childhood immunization coverage rates than states in which they are located. We conducted a secondary analysis of the National Immunization Survey (NIS) 2000 and 2006 of children 19-35 months old for 26 NIS-defined central cities and the rest of their respective states in order to examine patterns in early childhood immunization disparities between central cities and their respective states and the contextual factors associated with these disparities. We examined three measures of immunization disparities (absolute, difference, and ratio of change) and the patterns of disparity change with regard to selected contextual factors derived from the census. In 2000, immunization coverage in central cities was 68.3% and 74.7% in the rest of their states, a 6.4% disparity (t = 3.82, p < 0.000). Between 2000 and 2006, the overall city/state disparity narrowed to 3.5%, with the central city coverage up to 78.7% vs. 82.5% for the rest of state (t = 2.48, p = 0.017). However, changes in immunization disparities were not uniform: six cities narrowed, 14 had minimal change, and six widened. Central cities with a larger share of Hispanics experienced less reduction in disparities than other cities (beta = -4.2, t = -2.11, p = 0.047). Despite overall progress in childhood immunization coverage, most central cities still show significant disparities with respect to the rest of their states. Cities with larger Hispanic populations may need extra help in narrowing their disparities.