Social networks and the spread of epidemics

In addition to the modern web-based “social networks”, where contacts are only virtual, there is a more traditional network of physical contacts among individuals, which is ultimately responsible for the transmission of all types of diseases. In this paper, we introduce the basic models of networks used to describe the social contacts within a population. Then we study how to transfer the traditional epidemic models, based on the “homogeneous mixing” assumption, to the new framework. We will see that, moving from the classical to the network modelling approach, results become more complex and somehow unexpected, as the structure of the social network plays a fundamental role.