National Serologic Survey of Measles Immunity Among Persons 6 Years of Age or older, 1988-1994

Sonja S. Hutchins, MD, MPH,* Stephen C. Redd, MD,† Stephanie Schrag, PhD,‡ Deanna Kruszon-Moran, MS,§ Karen Wooten, MA,* Geraldine M. McQuillan, PhD,§ William Bellini, PhD,‡ Pamela A. Meyer, PhD,II Stephen Hadler, MD* * National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Georgia; † National Immunization Program, Centers for Disease Control and Prevention, now the National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia; ‡ National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; § National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland; II The Council of State and Territorial Epidemiologists, now the National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia

In This Article

Abstract and Introduction

Context: Measles incidence in the United States is at a record low, and indigenous transmission has been interrupted in each year since 1996, suggesting that measles is no longer endemic. A national estimate of measles immunity and an understanding of predictors of measles susceptibility are essential for assuring sustained elimination of endemic disease.

Objective: To assess patterns of immunity and to determine predictors of susceptibility to measles.

Design/Setting: Sera and data on participants from the third National Health and Nutrition Examination Survey (1988-1994) (NHANES III) were examined. NHANES III was a cross-sectional survey of a representative sample of the civilian, noninstitutionalized population of the United States.

Population: 20,100 persons 6 years of age or older were tested for measles-specific immunoglobulin G (IgG) antibody by an enzyme immunoassay.

Main Outcome Measure: Participants with serum positive for measles antibody were considered protected or immune to measles disease.

Results: Prevalence of measles immunity was 93%. Nearly all persons (99%) born in the prevaccine era (before 1957) were immune. Immunity declined among persons born in the vaccine era (after 1956) to 81% among those born in 1967-1976, and increased again to 89% among those born in 1977-1988. Among persons born in the vaccine era, independent predictors of measles susceptibility varied by birth cohort and included birth in the United States, residence in a noncrowded household, residence in a nonmetropolitan area, and, among males, non-Hispanic white and Mexican American race/ethnicity. Among adults 17 years of age or older, additional predictors of susceptibility included living at or above the poverty line and not currently being married.

Conclusions: Population immunity among persons 6 years of age or older is very high; however, as many as 15 million persons across the United States may lack humoral immunity. While it is unclear that the susceptible population can support continuous, indigenous transmission of measles, providers should follow current recommendations to evaluate the measles susceptibility of patients born in the vaccine era and vaccinate eligible patients.

As part of national and hemispheric initiatives, the United States established a goal to eliminate indigenous transmission of measles by the year 2000.[1,2] Before measles vaccines were licensed in the United States in 1963, more than 500,000 cases occurred each year.[3,4] Today, several decades later, the number of measles cases is at an all-time low of 100 cases reported in 1999, and surveillance data suggest that indigenous transmission has been interrupted in each year since 1996, suggesting that measles is no longer an endemic disease in the United States.[5,6,7,8,9,10,11,12] However, the importation of measles from other countries, coupled with susceptible populations of both infants younger than the age of routine vaccination and young adults, potentially threaten sustained elimination of endemic measles.[10,11,12,13] Moreover, measles epidemics are cyclic; an outbreak will occur when a sufficient level of susceptible persons is reached.

A national estimate of measles susceptibility provides crucial information for determining if current vaccination policies and programs will be effective in sustaining a nation free of endemic disease. To assess population immunity among persons ages 6 years and older, sera from NHANES III was tested. In addition, predictors of measles susceptibility were assessed to evaluate whether our current prevention strategies need refinement.

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