Persistent Low Immunization Coverage Among Inner-city Preschool Children Despite Access to Free Vaccine

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Abstract
Objective. To compare vaccination coverage among children 19 to 35 months of age from public housing developments where a free vaccine outreach program was in place with children residing elsewhere in the city. Design. A household survey using a multistage cluster sampling method to compare community areas which accounted for 80% of measles cases during 1989 (high-risk stratum), areas which accounted for the remaining 20% of cases (low-risk stratum), and public housing developments (public housing stratum) having free, on-site vaccination services. Setting. Inner-city Chicago households, April to May 1994. Outcome Variables. Antigen-specific and series-specific coverage based on written records. Results. Based on evaluation of 1244 children, citywide coverage for four doses of diphtheria-tetanus-pertussis vaccine, three doses of polio vaccine, and one dose of measles-containing vaccine (4:3:1) was 47% [95% confidence interval (CI), 40% to 55%]. Coverage was significantly lower among children residing in public housing (23%; 95% CI, 18% to 28%) compared with those residing in high-risk strata (45%; 95% CI, 38% to 52%) and low-risk strata (51%; 95% CI, 43% to 60%). Compared with white children (53%), coverage for the 4:3:1 series was lower among African-American children in public housing (29%) or outside public housing (36%). Moreover, 11% (95% CI, 8% to 14%) of children residing in public housing had never received any immunizations. Conclusions. African-American children throughout Chicago, particularly in public housing, remain at increased risk for vaccine-preventable diseases and should be targeted further for vaccination services. Vaccination coverage remains low several years after a major outbreak of measles and implementation of a free vaccine outreach program. Cluster surveys may be useful for monitoring vaccination coverage in high-risk urban settings.