Tetanus immunization status and immunologic response to a booster in an emergency department geriatric population

STUDY OBJECTIVES: Although effective procedures for the prevention of tetanus have long been available, serosurveys done since 1977 demonstrate that 49% to 66% of the elderly population lacks a protective antitoxin level (more than 0.01 IU/mL). This study was undertaken to assess the tetanus immunization status of patients presenting to an emergency department and to evaluate their immunologic response to a tetanus booster. SETTING: The study was conducted in a tertiary care ED. TYPE OF PARTICIPANTS: The patients enrolled were 65 or more years old and had breaks in their skin barriers. DESIGN: At each patient's initial presentation, pertinent demographic data and tetanus immunization history were recorded. The patient was then followed for 21 days. INTERVENTIONS: Each patient's antitoxin titer was determined on a serum sample by ELISA, and, if required by the Advisory Committee on Immunization Practices criteria, a booster was administered at the first visit. MEASUREMENTS AND MAIN RESULTS: Serum antitoxin assays were repeated on days 7, 14, and 21 after the initial visit until seroconversion (titer more than 0.01 IU/mL). Forty-four patients (55%) had protective levels at initial presentation, and in 36 (45%) the levels were not protective. Age and sex were not predictive of protection. Past military service and a definite history of three or more previous immunizations were good predictors of protection. Of 34 patients who were followed serially for inadequate initial titers, only 19 (56%) seroconverted by day 14. Patients who did not seroconvert were more likely to be older (P less than .05). CONCLUSIONS: This study demonstrated that a significant number of elderly patients lacked an initial protective level of tetanus antitoxin. Of these, 44% failed to seroconvert within 14 days and carried a potential risk of developing tetanus.