Shifting perspectives on host contact networks: From uniform, to heterogenous, and presently dynamic

Network epidemiology emphasizes the role of host-host contact, as prerequisite for pathogen transmission, for infectious disease dynamics. From this perspective, foundational models with mass action laws for contact rates can only describe fully connected host populations. Critical epidemic properties, it turns out, are driven by the type of contact network assumed--but these too suffer a limitation. For example, we show that cattle movements routed through livestock markets create fleeting connectivity between farms that is poorly approximated by static networks. The next leap forward will likely address dynamic contact networks forced by external drivers or coupled to the outbreak of disease.