Forty years and four surveys: How does our measuring measure up?

Abstract Objective: This article reviews four surveys methodologies that have been used over the past 40 years to assess immunization rates in young children in the United States. These methods include three national surveys: (1) United States Immunization Survey (1959–1985), which was first a household and then a telephone survey; (2) National Health Interview Survey (1991–present), which interviews people in their homes; and (3) National Immunization Survey (1994–present), a random-digit-dialing telephone survey. In addition, a series of retrospective school record surveys that used standard sampling and assessment methodologies were conducted nationally during 4 school years September 1990–May 1991. Methods: Federal publications, National Immunization Conference proceedings, and Centers for Disease Control and Prevention (CDC) internal reports regarding national immunization surveys were reviewed. The methodology used in each survey is presented, and selected examples of previously tabulated results are presented. Conclusions: The assessment of immunization coverage in American preschool children requires ongoing commitment and survey expertise. Over the past 40 years the CDC’s efforts to determine vaccination coverage in young children has evolved from the comparatively simple United States Immunization Survey to the current National Immunization Survey that utilizes sophisticated statistical and survey techniques to obtain the most-accurate results yet available.