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 2. Anti-polyribosyl-ribitol phosphate antibody concentrations in 2- to 4-year-old children, according to number of doses of acellular pertussis containing Haemophilus influenzae type b combination vaccines received in infancy. Proportion achieving different concentrations is shown.