FIG 2.
Results from multivariable logistic regression analysis of antibody response as a function of preimmunization titer adjusted for age, sex, and IgG level. The data shown represent the odds ratio of a 4-fold or greater increase in antibody titer as a function of the absolute preimmunization titer, starting at the lower limit of 1.3 μg/mL. As the absolute preimmunization titer value increases, the odds ratio of a 4-fold or greater response approaches zero for all serotypes. The solid line represents the mean value, and the dashed lines represent the 95% CIs.