An Assessment of the Quality of National Child Immunization Coverage Estimates in Population-based Surveys
Vaccination coverage surveys - Publication abstract: Background This study aims to assess of the quality of child immunization coverage estimates obtained in 101 national population-based surveys in mostly developing countries. Methods The Demographic and Health Surveys (DHS) and UNICEF's Multiple Indicator Cluster Sample (MICS) surveys provide national immunization coverage estimates for children aged 12-23 months once every three to five years in many developing countries. The data are collected by interview from a nationally representative sample of households. 83 DHS and 18 MICS surveys were included. Findings 85% of mothers reported that they had ever received a health card for their child. 81% still had the card at the time of the interview, and nearly two-thirds of these presented the card to the interviewer. Cards were therefore observed for 55% of children overall. Rural and less educated mothers were less likely to report receiving health cards. Recall of additional immunizations by mothers that presented a card ranged from 1 to 3%. Recall of immunizations by mothers who reported never receiving a card ranged from 9 to 32%. Coverage among those who did not show a card rarely exceeded coverage among those who did, and there was good correlation between DPT and OPV doses received according to health card and recall data. Conclusion Though maternal recall data are known to be less accurate than health card data, we found no major systematic weaknesses in recall and believe that inclusion of recall data yields more accurate coverage estimates.