Individual pneumococcal serotype-specific IgG antibody titers before and after challenge.

<p>Graphs present scatterplots of pneumococcal serotype-specific IgG antibody titers pre- and 1 month post-challenge with a low dose of PPV23 for individual children in the groups not vaccinated with any pneumococcal vaccines (grey triangles), vaccinated with PCV7 and PPV23 (black circles), and vaccinated with PPV23 only (open squares). Serotypes with an asterisk (*) are included in PPV23 only, while other serotypes are included in both PCV7 and PPV23. For children whose antibody titers are higher post- than pre-challenge (increase in antibody titer) data points lie above the line; for children with similar titers before and after challenge data points cluster around the reference line; and for children whose antibody titers were lower 1month after challenge than before data points lie under the reference line. The p-values included in the graphs correspond with non-parametric analysis of paired pre- and post-challenge responses within the treatment groups (Wilcoxon Signed Rank Test).