Fig. 2.

Kinetics of pertussis antibody responses over a 3-year period after booster vaccination with recombinant acellular pertussis or chemically detoxified Tdap.

Graphs show geometric mean concentrations or titres (and 95% confidence intervals) of IgG antibodies against pertussis toxin (PT-IgG), filamentous hemagglutinin (FHA-IgG), and PT-neutralising antibodies (PT-Nab) for individuals vaccinated at Day 0 (pre-vaccination) with recombinant aP_gen vaccine (blue line; circles), recombinant TdaP_gen vaccine (purple line; triangles), or comparator Tdap_chem vaccine (orange line; squares) with evaluable data at different time points. Differences in GMCs between groups were compared using the Bonferroni post-hoc test, with observed p-values corresponding to a) p < 0·0001; b) p = 0.0001; c) p = 0·0015, and d) p = 0·0047.