Fig. 1: Illustration of the dynamics of interacting contagions.

A Schematic representation of two synergistic contagions (blue and orange) spreading synergistically through a network. Co-infections, shown in pink, are needed to sustain the contagion and are aided by clustering. B Phase transition of various types of contagions. While independent contagions display continuous transitions, synergistic contagions can build up transmission potential, which leads to discontinuous transitions reminiscent of physical systems where latent heat accumulates. C Growth rate of synergistic (pink), independent (black), and antagonistic (green) contagions. Synergistic contagions tend to grow superexponentially since they get more likely to interact as they spread further.