CDC's National Immunization Survey

Children should receive most of their immunizations before they reach 19 months old. To monitor the extent to which this goal is met nationwide, the Centers for Disease Control and Prevention (CDC) has, since 1991, administered a supplement to the National Health Interview Survey. In 1994, CDC decided to centralize the collection of immunization coverage data for preschoolers in each state and some urban areas. That year, CDC initiated the National Immunization Survey, which was designed to produce current and comparable immunization coverage estimates for children aged 19 to 35 months in each state and 28 urban areas receiving CDC funds. Unlike the National Health Interview Survey, which is a face-to-face household survey, the National Immunization Survey is conducted by telephone. Although national, antigen-specific immunization rates are generally high, some areas remain at continued risk of disease outbreaks (sometimes called "pockets of need") because they have concentrations of children who have not received timely vaccinations. This report assesses (1) the cost of the National Immunization Survey, (2) the methods used by CDC to conduct the survey, and (3) the utility of the survey in identifying "pockets" of children in need of more timely immunization.

GAO found that: (1) CDC designed NIS for monitoring state progress in achieving child immunization objectives, comparing coverage rates across states, and awarding incentive funds; (2) CDC estimates and contractor invoices indicate that NIS costs for fiscal year (FY) 1995, including extraordinary expenses incurred when 1994 survey participants were reinterviewed, were about $13 million; (3) although CDC anticipates that survey costs will decrease in the future, it has requested $16 million for NIS administration for FY 1997; (4) the two-phase survey methodology, which gathers information by telephone from households and immunization providers, excludes households that lack a telephone, may not accurately represent the overall population, and is limited by response accuracy; (5) NIS has not achieved sufficient precision in its survey estimates to detect modest changes that occur in most coverage levels; (6) CDC considers the identification of groups of children in need of more timely immunization as a state rather than a federal responsibility and has not designed and does not use NIS to make such identifications; and (7) interviews with state officials indicate that NIS is not useful in helping states to diagnose problems in immunization activities, target efforts, or design interventions.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.

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