Abstract
In order to target the appropriate age population for booster vaccination, we examined the antibody titres against pertussis toxin (PT) in different age groups in immunized and non-immunized individuals. In the immunized population, the highest anti-PT levels were observed in the 0- to 2-y age group and the lowest in the teenager and young adult groups. In contrast, in the control group, anti-PT levels were minimal in infants and young children, increasing in adolescence and early adulthood, and waning after 30 y of age. Antibody levels >30 U/ml were observed with higher frequency in children <2 y of age, in individuals with complete vaccination history and in non-immunized individuals. These findings may have important implications in optimizing vaccination policies.