MATERNAL RECALL ERROR OF CHILD VACCINATION STATUS IN A DEVELOPING-NATION

In the absence of vaccination card data, Expanded Program on Immunizat ion (EPI) managers sometimes ask mothers for their children's vaccinat ion histories. The magnitude of maternal recall error and its potentia l impact on public health policy has not been investigated. In this st udy of 1171 Costa Rican mothers, we compare mother's recall with vacci nation card data for their children younger than 3 years. Analyses of vaccination coverage distributions constructed with recall and vaccina tion-card data show that recall can be used to estimate population cov erage. Although the two data sources are correlated (r = .71), the mag nitude of their difference can affect the identification of the vaccin ation status of an individual child. Maternal recall error was greater than two doses 14% of the time. This error is negatively correlated w ith the number of doses recorded on the vaccination card (r = -.61) an d is weakly correlated with the child's age (r = -.35). Mothers tended to remember accurately the vaccination status of children younger tha n 6 months, but with older children, the larger the number of doses ac tually received, the more the mother underestimated the number of dose s. No other variables explained recall error. Therefore, reliance on m aternal recall could lead to revaccinating children who are already pr otected, leaving at risk those most vulnerable to vaccine-preventable diseases.