Figure 1.

Trivalent inactivated influenza vaccine effectiveness (VE) against influenza A(H3N2) (A) and influenza B/Yamagata (B), by year of age among persons aged 1–75 years. VE estimates were derived by including an interaction term between age and current-season vaccination status in the logistic model, in which age was represented as a restricted cubic spline function with 5 knots based on percentiles. The confidence intervals represent the uncertainty around the point estimate at each age. VE data are adjusted for network site, subject age, presence of high-risk health conditions, and calendar time (2-week intervals).