The effect of policy changes on hepatitis A vaccine uptake in Arizona children, 1995-2008

In 1995, the first hepatitis A vaccines became available for use. At that time, Arizona had the highest hepatitis A incidence of all 50 states. During that same time period, the Arizona State Immunization Information System (ASIIS) was created to collect information on all immunizations given in the state. Four state-level hepatitis A vaccination policies were enacted according to Centers for Disease Control and Prevention recommendations and local initiatives from 1996 to 2005. Our primary objective was to assess the impact of these policies on vaccine uptake in children.

Immunization records from ASIIS were used to calculate yearly coverage of children with at least one reported hepatitis A vaccination between 1995 and 2008. Proportions vaccinated were calculated by age group (12-23 months, 24-59 months, 5-9 years, 10-14 years, and 15-19 years) for three regions: Maricopa County; Apache and Navajo counties; and the remaining 12 Arizona counties, which were grouped as one to reflect different target groups for the four policies examined. We calculated percent changes from before and after each policy implementation.

Significantly different percent changes were detected among the three regions that related to the four policies implemented. Percent change in uptake was consistently higher in the regions that were targeted for that specific policy.

Analysis of ASIIS data revealed a major effect of hepatitis A policy recommendations on vaccine uptake in Arizona. Targeting high-risk populations through vaccine recommendations and child care entry requirements was highly successful in achieving higher vaccination coverage.