Serologic immunity to diphtheria and tetanus in the United States.

BACKGROUND

Serologic data on diseases that are preventable by vaccine are useful to evaluate the success of immunization programs and to identify susceptible subgroups.

OBJECTIVE

To provide national estimates of immunity to diphtheria and tetanus by measurement of serum antibody levels.

DESIGN

Examination of data from the Third National Health and Nutrition Examination Survey, a representative cross-sectional sample of the U.S. population.

SETTING

89 randomly selected locations throughout the United States.

PARTICIPANTS

18 045 persons 6 years of age or older who were examined from 1988 to 1994.

MEASUREMENTS: Serum samples obtained at a single time point were tested for diphtheria and tetanus antitoxin.

RESULTS

Overall, 60.5% of Americans 6 years of age or older had fully protective levels of diphtheria antibody (> or =0.10 IU/mL) and 72.3% had protective levels of tetanus antibody (> 0.15 IU/mL). Ninety-one percent of Americans 6 to 11 years of age had protective levels of both diphtheria and tetanus antibody; this proportion decreased to approximately 30% among persons 70 years of age (29.5% for diphtheria and 31.0% for tetanus). Adult Mexican-Americans were slightly less likely to have protective levels of antibody to both toxins. Only 47% of persons 20 years of age or older had levels that were protective against both diseases, and only 63% of adults who were protected against tetanus were also protected against diphtheria.

CONCLUSIONS

A substantial proportion of adults in the United States do not have antibody levels that are protective against diphtheria and tetanus. In addition, although the recommended vaccine is a combination of tetanus and diphtheria, only 63% of adults with protective antibody to tetanus also had protective antibody to diphtheria.