Results
A total of 1564 nasopharyngeal swabs were available for molecular serotyping from the initial 600 infants enrolled between Jan 9 and Sept 20, 2017 (100 were randomly assigned to each group; Comparing all three PCV13 groups, there was no significant difference at 9 months of age in the prevalence of overall pneumococcal (70–88%) and non-vaccine-serotype (51–67%) colonisation (Prevalence of PCV13 vaccine serotypes including serotypes or serogroups 1, 3, 4, 5, 6A, 6B, 7A or 7F, 9A or 9V, 14, 18B or 18C, 19A, 19F, and 23F (differences between serogroups are shown on There was no significant difference in the incidence of new acquisition for PCV13 vaccine serotypes at 15 months or 18 months of age in the 2 + 1 group (13·2 per 100 children at 15 months of age and 11·7 per 100 children at 18 months of age) compared with both the 14-week 1 + 1 group (6·7 per 100 children and 10·6 per 100 children) and the 6-week 1 + 1 group (6·1 per 100 children and 18·0 per 100 children; At 15 months of age, the prevalence of overall Prevalence of PCV10 vaccine serotypes including serotypes and serogroups 1, 4, 5, 6B, 7A or 7F, 9A or 9V, 14, 18B or 18C, 19F, and 23F (differences between serogroups shown on There was no significant difference in the incidence of new acquisition of PCV10 vaccine and non-vaccine serotypes across the study groups (We analysed pneumococcal colonisation in children in the 2 + 1 group for either the PCV10 or PCV13 formulation. At 9 months of age (pre-booster dose), the prevalence of overall Prevalence of PCV10 vaccine serotypes including serotypes or serogroups 1, 4, 5, 6B, 7A or 7F, 9A or 9V, 14, 18B or 18C, 19F, and 23F (differences between serogroups are shown on The percentage of children with serotype-specific capsular IgG geometric mean concentrations above the putative protective correlates against colonisation at 1 month after the booster ranged from 76% to 99% in the 14-week 1 + 1 PCV13 group compared with 76–99% in the 6-week 1 + 1 group and 80–100% in the 2 + 1 PCV13 group (Proportion of serum PCV serotype-specific capsular IgG geometric mean concentrations above the putative threshold associated with a risk reduction of serotype-specific colonisation measured 1 month after the booster in children receiving PCV13Data are n (%; 95% CI) unless otherwise stated. The 6-week 1+1 group received a priming dose at 6 weeks of age and a booster at 9 months of age. The 14-week 1+1 group received a priming dose at 14 weeks of age and a booster at 9 months of age. The 2+1 group received priming doses at 6 weeks and 14 weeks of age and a booster at 9 months of age. PCV=pneumococcal conjugate vaccine. PCV10=ten-valent PCV. PCV13=13-valent PCV.Putative correlate of protection against PCV10 serotype-specific colonisation proposed by Voysey and colleaguesComparing proportion of above putative correlate of protection between the 6-week 1+1 group and the 2+1 group.Comparing proportion of above putative correlate of protection between the 14-week 1+1 group and the 2+1 group.Comparisons that met the non-inferiority criterion.A similar percentage of children in the PCV10 2 + 1 and both 1 + 1 groups had serotype-specific capsular IgG above the putative correlates proposed by Voysey and colleagues,Proportion of serum PCV serotype-specific capsular IgG geometric mean concentrations above the putative threshold associated with a risk reduction of serotype-specific colonisation measured 1 month after the booster in children receiving PCV10Data are n (%; 95% CI) unless otherwise stated. The 6-week 1+1 group received a priming dose at 6 weeks of age and a booster at 9 months of age. The 14-week 1+1 group received a priming dose at 14 weeks of age and a booster at 9 months of age. The 2+1 group received priming doses at 6 weeks and 14 weeks of age and a booster at 9 months of age. PCV=pneumococcal conjugate vaccine. PCV10=ten-valent PCV.Putative correlate of protection against PCV10 serotype-specific colonisation proposed by Voysey and colleaguesComparing proportion of above putative correlate of protection between the 6-week 1+1 group and the 2+1 group.Comparing proportion of above putative correlate of protection between the 14-week 1+1 group and the 2+1 group.Comparisons that met the non-inferiority criterion.