14. Transmission on Networks

Following the initial exploration of the simplest SIR model in Chap. 2, various chapters have explored a number of elaborations that are important in order to understand many aspects of infectious disease dynamics such as age-structure, seasonality, and more complex compartmental flows among individuals within a community. In addition to such heterogeneities which can be categorized according to covariates/cofactors (age, month, hospital versus community, etc.), there is often substantial variation that defies such classification. Lloyd-Smith et al. (2005), for example, identified significant heterogeneities from superspreading events during the 2003 SARS outbreak. Woolhouse et al. (1997) suggested a 80/20 rule-of-thumb: for many infections a core of 20% of infected accounts for 80% of onwards transmission.