Low seroprevalence of diphtheria, tetanus and pertussis in ambulatory adult patients: the need for lifelong vaccination

Abstract

Background: Tetanus, diphtheria, pertussis and measles are vaccine preventable diseases that have been reported to cause morbidity and mortality in adult population in the recent years. We aimed to document the seropositivity rates and vaccination indication for these four vaccine preventable diseases among adult and elderly patients who were seen as outpatients in a university hospital.

Methods: Blood samples for tetanus, diphtheria, pertussis and measles antibodies were obtained. Results were evaluated with regards to protection levels and booster vaccine indications according to the cut-off values.

Results: A total of 1367 patients consented for the study and 1303 blood samples were available for analysis at the end of the study. The antibody levels against measles conferred protection in 98% of patients. However, 65% of the patients had no protection for diphtheria, 69% had no protection for tetanus and 90% of the patients had no protection for pertussis. Only 1.3% of the study population had seropositivity against three of the diseases-Tdap booster was indicated in 98.7%. Multivariable logistic regression showed that tetanus protection decreased with increasing age. Having a chronic disease was associated with a lower rate of protective antibodies for pertussis.

Conclusions: We demonstrated very low rates of protection against three of the vaccine preventable diseases of childhood-diphtheria, pertussis and tetanus. Booster vaccinations are required in adult life in accordance with national and international adult vaccination guidelines. The concept of "lifelong vaccination" should be implemented and every encounter with the patient should be regarded as a chance for catch-up.

Keywords: Diphtheria; Measles; Pertussis; Seroprevalance; Tetanus; Vaccine.