FIGURE 3.

Incidence of ARI stratified by infant age and season. The incidence of ARI in the 2 study sites was calculated within strata of infant age (open circles ≤6 months or filled triangles >6 months) and calendar quarter (Q), to account for any potential bias introduced by time-varying differences in the age-structure of the cohort (see Fig., Supplemental Digital Content 2, http://links.lww.com/INF/C71). Ninety-five percent confidence intervals around the stratum-specific incidence estimates are shown.