Nik G. Johnson*, Jens U. Ruggeberg*, Gail F. Balfour*, Y. Chen Lee†, Helen Liddy‡, Diane Irving‡, Joanna Sheldon‡, Mary P.E. Slack§, Andrew J. Pollard†, and Paul T. Heath*
Figure 1. Geometric mean anti-polyribosyl-ribitol phosphate antibody concentration before booster (95% confidence intervals) in 2- to 4-year-old children, according to number of doses of acellular pertussis (aP) containing Haemophilus influenzae type b combination vaccines received in infancy. Number of participants is shown in parentheses. GMC, geometric mean concentration.