Response to diphtheria booster vaccination in healthy adults: vaccine trial.

The diphtheria epidemic in eastern Europe and the worldwide increase in diphtheria morbidity have sparked discussion on whether people in western Europe are adequately protected. 2 In western Europe, the effectiveness of long term protection afforded by immunisation programmes is under debate. In Belgium, the national immunisation programme against diphtheria was introduced in 1959. Vaccination was recommended for all infants, and a catch up programme for children up to the age of 15 years was also instituted. The programme comprises four doses of toxoid, given at age 3, 4, 5, and 15 months. The vaccine is a combination of diphtheria, pertussis, and tetanus toxins, and 95% of children are covered. We evaluated the effectiveness of the current recommended adult booster immunisation of a single, low dose diphtheria vaccine.