Proportion of 3-5-year-old children with pneumococcal serotype IgG antibody titers ≥ 0.35 μg/ml and ≥ 1 μg/ml one month after low-dose PPV23 challenge.

<p>Proportion of 3-5-year-old children with pneumococcal serotype IgG antibody titers ≥ 0.35 μg/ml and ≥ 1 μg/ml one month after low-dose PPV23 challenge.</p

Flowchart for children in the study.

<p>A flowchart of the completed preceding neonatal PCV7 trial is published elsewhere [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185877#pone.0185877.ref008" target="_blank">8</a>]. A total of 132 of 259 children who participated in the previous PCV7 study and who were vaccinated with PPV23 at 9 months of age were included in this study. One hundred and twenty seven children could not be enrolled for reasons summarized in Fig 1, including death; being too old according to pre-defined inclusion criteria; illness; migration to an area outside the study’s reach capacities; not located; and refusal. A total of 121 of 136 potential community controls who were assented to participate in the study were included in the final analysis: of the 15 not included, three children were over age; three did not consent; three could not be relocated and blood collection pre-challenge was not successful for six children. Post-challenge data were not available for 41 children for reasons summarized. <i>N</i> is Neonatal PCV7 group; <i>I</i> is Infant PCV7 group; <i>C</i> is control group (no PCV7).</p

Generalised estimating equations studying associations between change in serotype-specific antibody titers in response to challenge and pneumococcal vaccine history and pre-challenge antibody titers.

<p>Generalised estimating equations studying associations between change in serotype-specific antibody titers in response to challenge and pneumococcal vaccine history and pre-challenge antibody titers.</p

Pneumococcal serotype-specific IgG antibody titers before and after challenge.

<p>Serum antibody titers were assessed in 3-5-year-old children who had received PCV7 and PPV23 as infants (white bars; n = 100 /n = 86), who had received only PPV23 as infants (grey bars; n = 32 /n = 28), or who had not received pneumococcal vaccines (striped bars; n = 121 pre-challenge/ n = 98 post-challenge) (A) before and (B) after challenge with a low dose of PPV23. Data are presented as geometric mean titers and 95% confidence intervals. Serotype-specific geometric mean titers before or after challenge were compared between each group using Mann-Whitney U test. * p < 0.05.</p