Objective: To check if antitetanus immunity after a correct vaccination lasts the anticipated 10 years.
Design: Sero-epidemiological crossover study. Determination of tetanus antitoxin by the ELISA method.
Setting: The town of Barrado in Cáceres.
Patients and other participants: 136 adult men and women (average age 54.6 +/- 15.9 years; range, 24 to 87) who had received their most recent vaccination during a 1981-1982 campaign. 71.32% received three doses.
Measurements and main results: 82.35% +/- 6.40 of the sera analysed (percentage +/- C.I. 95%) maintained adequate levels of protection (> or = 0.01 Ui/ml). 100% of those under 35, revaccinated in 1980-81 because they were ELISA negative in spite of earlier school vaccination, were protected. The average concentrations did not differ significantly by gender and age-groups, although a tendency to decrease with age was noted.
Conclusions: Anti-tetanus vaccination in the individuals studied provided lasting protection, detectable for 10 years in 76-89% of cases. This level of effectiveness lends support to the criterion of administering back-up doses every 10 years.