Pertussis seroprevalence in different age groups in Greece.

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.