Differences in avidity of IgG antibodies to pertussis toxin after acellular pertussis booster vaccination and natural infection

► IgG-anti-pertussis toxin antibodies are specific for B. pertussis infection. ► We compared avidity index of IgG-anti-pertussis toxin antibodies after acellular booster vaccination and B. pertussis infection. ► There is a difference in avidity index of IgG-anti-PT antibodies after infection and after booster vaccination with acellular pertussis vaccine (Boostrix).