Estimating Vaccination Coverage in the U.S. Commonwealth of the Northern Mariana Islands: Validity of Household-Retained Vaccination Cards and Parental Recall
Elizabeth Luman, National Center for Immunization and Respiratory Diseases, Centers for Disease Control, 1600 Clifton Rd MS-E05, Atlanta, GA, USA, Tove Ryman, Global Immunization Division, NCIRD, Centers for Disease Control and Prevention, 1600 Clifton Rd MS-E05, Atlanta, GA, USA, and Mariana Sablan, Division of Public Health, CNMI Department of Health, Saipan, CNMI, USA.
Learning Objectives for this Presentation: By the end of the presentation, participants will be able to: • understand the importance of identifying reliable sources of vaccination history information and • understand the potential limitations of vaccination coverage estimated from surveys that rely on household-retained cards and/or parental recall.
Background: Public health programs rely on household-survey estimates of vaccination coverage as a basis of programmatic and policy decisions; however, the validity of estimates derived from household-retained vaccination cards and parental recall has not been thoroughly evaluated.
Objectives: Compare results from household data sources (cards and parental recall) to medical record sources for the same children.
Methods: Using data from a vaccination coverage survey conducted in the U.S. Commonwealth of the Northern Mariana Islands in July 2005, we calculated the percentage of children aged 1, 2, and 6 years who received all vaccines recommended by age 12 months, 24 months, and for school entry, respectively.
Results: Coverage estimated based on vaccination cards (assuming that children without cards were not completely vaccinated) was 14%-30% in the three age groups compared to 78%-91% for the same children based on medical records. When cards were supplemented by parental recall, estimates were 51%-53%. Among children with a vaccination card (71% of children aged 1 and 2 years, 58% of those aged 6 years), card-estimated coverage was 25%-43%. Concordance, sensitivity, specificity, positive and negative predictive values, and kappa statistics generally indicated poor agreement between household and medical record sources.
Conclusions: These results show that household-retained vaccination cards and parental recall were insufficient sources of information for estimating vaccination coverage in this population. This study emphasizes the importance of identifying reliable sources of vaccination history information and reinforces the need for awareness of the potential limitations of vaccination coverage estimated from surveys that rely on household-retained cards and/or parental recall.