Hepatitis A 2004 vaccination in children: methods and findings of a survey in two states

Hepatitis A vaccine coverage estimates needed for surveillance and vaccine policy decisions are not readily available for children older than 35 months or for adolescents. This article reports methodology developed for obtaining such estimates by telephone survey with and without provider record verification. A random-digit-dial telephone survey with provider verification was conducted in Arizona and Oregon in 2004-2005 to obtain coverage estimates for children aged 2.5 to 15 years based on parental reports from telephone survey data alone, and from multiple logistic regressions using both telephone survey and provider data. Analysis was performed during 2006. Vaccination information was collected from parents of 1266 children, and provider verification from 488. Telephone survey and provider record-based hepatitis A vaccine coverage (one or more doses) was 60% and 65%, respectively, in Arizona, and 39% and 26%, respectively, in Oregon. Children who were younger, lived in metropolitan areas, or were Hispanic or nonwhite had significantly higher coverage; parents with immunization records provided more-accurate information. While a logistic model-based estimator developed using both parent and provider data performed slightly better than the estimator based on parent data alone, they differed mostly in the subgroups that had small sample sizes. These are the first statewide provider-verified hepatitis A vaccine coverage estimates for children older than 35 months and indicate that telephone survey estimates as developed using this methodology could prove useful for immunization surveillance activities if interpreted cautiously.