Low immunization uptake rates in an inner-city health district: fact or fiction?

Immunization uptake rates are assuming considerable importance as performance indicators for district health authorities (DHAs) and general practitioners (GPs). Data from the Cover of Vaccination Evaluated Rapidly (COVER) programme suggest that immunization uptake rates in innercity districts are well below the 90 per cent target. Using Parkside DHA, a district with consistently poor uptake, as an example, this paper has examined the accuracy of the Child Health Computer (CHC) records on which the COVER figures are based. In October 1989 a cohort of 1485 children born between April and June 1988 were identified. The 462 children identified by the CHC as immunization defaulters (using diphtheria and tetanus immunizations) were followed up by contacting child health clinics, GP surgeries and parents. This exercise revealed that 195 children were in fact immunized and 176 children were erroneously listed, largely because they were no longer resident at the address given. Only a small proportion of this information had reached the CHC by the end of the follow-up period. In addition to high population mobility, information inaccuracies appeared to be caused partly by a failure in data transfer between GPs and the DHA and by failures in data transfer between districts. Overall, the results of the study suggest that there is a considerable discrepancy between actual and recorded immunization uptake levels in Parkside and probably other inner-city areas. This will have a considerable impact on GPs and other health professionals who are striving to achieve 90 per cent targets.