Statistical analysis
vaccine-type carriage, Vaccine-type carriage
OIS
Sample size calculations were based on the reduction in vaccine-type carriage at 24 months comparing vaccinated and unvaccinated groups and the total feasible study size. The allocation ratio of 4:4:4:4:9 maximises the power for a total sample size of 2500, providing 82% power to detect a 40% reduction in vaccine-type carriage in each intervention group compared with controls, with a two-sided type I error rate of 5%. We assumed 15% vaccine-type carriage prevalence among unvaccinated participants at 24 months and 10% loss to follow-up, based on a previous trialCarriage prevalence was presented as percentages with 95% CIs. The percent reduction in vaccine-type carriage, or vaccine efficacy against carriage, was calculated for each of the intervention groups compared with unvaccinated participants as (1 – prevalence ratio) × 100, both as a crude estimate and adjusted for the stratification variable district. Vaccine-type carriage prevalence was also compared between the PCV10 and PCV13 groups (in the same schedule) and between the 0 + 1 and 1 + 1 groups (with the same vaccine). Between-group comparisons of vaccine-type carriage were based on χSerotype-specific IgG data were summarised as geometric mean antibody concentrations (GMCs) with 95% CIs, and the percentage of participants with protective antibody concentrations (defined as ≥0·35 μg per mL) with 95% CIs. Opsonophagocytic assay data were summarised as geometric mean opsonisation indices (GMOIs) with 95% CIs, and the percentage of participants with protective functional antibody concentrations (defined as opsonisation indices [OIs] ≥8) with 95% CIs. Between-group comparisons were based on independent Data collection, entry, and management processes have been described previously.