National serologic survey of measles immunity among persons 6 years of age or older, 1988-1994

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.

Timing and effectiveness of requirements for a second dose of measles vaccine

OBJECTIVE

Previous measles elimination goals have failed in the United States despite high coverage of schoolchildren with a single dose of measles vaccine. Since 1989 advisory groups have recommended that schoolchildren receive a second dose of measles vaccine as part of a revised strategy to eliminate measles from the US. States have responded by phasing in requirements for a second dose of measles vaccine at school entry for various age groups at primary school entrance, secondary school entrance or both. The purpose of this analysis was to evaluate the effectiveness of the requirements for a second dose of measles vaccine and to determine whether a primary or secondary school entrance requirement was more effective in lowering measles incidence.

METHODS

Using national surveillance data we examined the influence of state requirements for the second dose of measles vaccine on measles incidence from 1993 through 1995.

RESULTS

Overall measles incidence was lower in states that had a requirement for a second dose of measles vaccine at either primary school entrance [relative risk (RR) = 0.35; 95% confidence interval, 0.25 to 0.49] or secondary school entrance (RR = 0.38; 95% confidence interval 0.29 to 0.50), compared with states without a second dose requirement. Incidence was lowest in states that required a second dose of measles vaccine at both primary and secondary school entrance (RR = 0.22; 95% confidence interval, 0.13 to 0.37).

CONCLUSIONS

Our findings demonstrate that a requirement for a second dose of measles vaccine at either primary or secondary school entrance is effective in lowering measles incidence, with a greater reduction occurring in states where the second dose is required for both age groups.

AIDS knowledge gaps: results from the first decade of the epidemic and implications for future public information efforts

Throughout the first decade of AIDS, certain populations have been disproportionately affected by its spread, particularly men, blacks, Hispanics, and the young. Just as there are population differences in the spread of the disease, there are differences in knowledge about the disease as well. This article applies the knowledge gap framework to examine the nature and magnitude of gaps in knowledge among different populations. The analysis shows that persons of low education lag behind other groups in true-transmission knowledge (i.e., knowledge about ways in which HIV/AIDS actually is transmitted) and false-transmission knowledge (i.e., misconceptions about how the disease is spread).