Relative susceptibility to infection.

<p>(A) Average value of the age-specific susceptibility to infection in age groups 5–14 years, 15–64 years and 65+ years, relative to that of the class 0–4 years. Vertical lines represent 95% CI. Colors refer to the contact matrix assumed, namely red for CM1 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074785#pone.0074785-Fumanelli1" target="_blank">[39]</a>, blue for CM2 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074785#pone.0074785-Iozzi1" target="_blank">[38]</a> and green for CM3 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074785#pone.0074785-Mossong1" target="_blank">[37]</a>. In this panel we assume that individuals are seropositive when HI titre is ≥40; in addition we assume that at the beginning of the simulations there are no fully immune individuals. (B) as A, but we assume that individuals are seropositive when HI titre is ≥10. (C) as A, but assuming pre-existing full immunity in the different age groups as obtained by the analysis of pre-pandemic sera. (D) as B, but assuming pre-existing full immunity in the different age groups as obtained by the analysis of pre-pandemic sera.