Demographic and network properties in a randomly picked simulation on 23 September 2012 (i.e. at the end of the initialization period), a day of the year on which the seasonal variation factor is 1.0 (i.e. the transmission potential reaches its all year average). This day precedes the annual vaccination period and the main transmission period. (a) Demographic structure of Germany; (b) average number of contacts per individual; (c) expected number of individuals who are infected by a single case whose age is given on the horizontal axis (averaged over the 4 influenza strains; the high number of expected infections caused by children derives from their long infectious period, their high connectivity and the immunity status of their contacts).