Interaction among cross-immunity generated by primary infection and vaccination: structural cross-immunity on annual emergence probability and size of pandemic.

<p>The x-axis <i>φ:ψ:φ</i>_V<i>:ψ</i>_V represents the structural cross-immunity. Other parameters as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114637#pone-0114637-t001" target="_blank">Table 1</a>. In view of the assumption that vaccine can fully protect against infection with target endemic strain, the situation of <i>φ</i>_V<i> = ψ</i>_V = 0 does not imply no effect of vaccination.