Fig. 1.

Proportions of epidemic viruses sampled in the pre-target seasons with greater (blue), same (red), and smaller (green) average antigenic distances to those sampled in the target seasons of 2001.0 to 2014.5, in comparison to the actual vaccines (left), the center-of-mass strains (middle), and the strains identified by the fitness model (right). Note that the results of the fitness model could be obtained only for the target seasons of 2011.0 to 2014.5.