Error bars represent the 95% confidence interval around the mean. The proportion of unclassified reads significantly differed at the p=0.05 level between treatment and control children aged 15–30 months by a two-sided, two-sample t-test, but not among other age strata. The number of biologically independent samples considered for each age strata is as follows: 6–14 months, n=27; 15–30 months, n=51; 31–61 months, n=52.