n order to impede the increase of pertussis incidence in the adolescent group, a school-leaving booster dose at the age of 14-16 years will be introduced in Sweden in 2016. Preceding this introduction an open-label, randomized, multicentre clinical trial without control group and blinded analysis was performed, investigating both safety and immunogenicity. Reported here are the memory B-cell and the serological responses detected in a smaller cohort (n=34) of the 230 subjects recruited to the study. All subjects had a primary vaccination consisting of three doses of DTaP5 (diphtheria, tetanus and 5-component pertussis vaccine) at 3, 5 and 12 months of age as well as a Tdap5 booster dose (tetanus, low dose diphtheria and pertussis 5-component vaccine) at 5½ years. In this study the subjects were randomized and received either a Tdap1 or a Tdap5 booster. Of the 230 participants, 34 subjects had available samples for evaluation of IgG-producing memory B-cell- responses. Both vaccine groups had significant increases in pertussis toxin-specific serum IgG-levels but only the 1-component group showed significant increases of pertussis toxin-specific memory B cells. The 5-component group had significant increases in filamentous hemagglutinin- and pertactin-specific memory B-cells and serum IgG-levels; this was not seen in the 1-component group, as expected. In conclusion, this study shows that a 5th consecutive dose of an acellularpertussis vaccine induces B-cell responses in vaccinated adolescents. Trial registration: EudraCT Number 2008-008195-13. Clinical Trials.gov identifier: NCT 00870350.
Journal:Clin Vaccine Immunol. 2014