Decennial diphtheria-tetanus adult boosters: are they really necessary?

Available epidemiological data shows that an average number of 59 cases of tetanus per year are still reported in Italy. Most of cases (80.2%) occur in subjects > 64 years-old. Furthermore, the proportion of females among subjects ≥ 65 years-old is significantly higher than males (87.7% vs. 64.4%, p < 0.0001). Seroprevalence data show that the percentage of subjects with protective tetanus antibody levels (> 0.1 IU/ml) decreases with increasing age. Most people aged ≥ 65 years are unprotected. The antibody levels are higher in males than females (p < 0.001) in subjects > 25 years-old. Conversely, extensive childhood immunization and adequate boosting vaccination of adults led to the near-elimination of diphtheria in Western countries. The current Italian National Immunization Prevention Plan 2012- 2014 recommends the administration of a primary vaccine course in the first year of life and booster at the preschool age, in adolescents and in adults every 10 years. Nevertheless, the need for decennial booster doses is debated by some experts, who state that the best time to offer a single dose of vaccine against tetanus and diphtheria is the age of 50, since low levels of antibody titers are observed. Considering the availability of combined vaccines against diphtheria, tetanus and pertussis (DTaP or dTaP), and the increasing incidence of pertussis in infants, who are at highest risk of serious complications, in adolescents and in adults, some countries have introduced decennial dTaP in the adults immunization schedule. It is desirable that this recommendation is also introduced in the future Italian Immunization Prevention Plan. The present review overviews the epidemiological data and the immunization strategies against tetanus, diphtheria and pertussis in Italy, discussing the rationale not only of decennial dT booster but also of the dTaP booster.