Effect of Small‐World Networks on Epidemic Propagation and Intervention

Abstract

The small‐world network, characterized by special structural properties of high connectivity and clustering, is one of the highlights in recent advances in network science and has the potential to model a variety of social contact networks. In an attempt to better understand how these structural properties of small‐world networks affect epidemic propagation and intervention, this article uses an agent‐based approach to investigate the interplay between an epidemic process and its underlying network structure. Small‐world networks are derived from a network “rewiring” process, which readjusts edges in a completely regular two‐dimensional network by different rewiring probabilities (0–1) to produce a spectrum of modified networks on which an agent‐based simulation of epidemic propagation can be conducted. A comparison of simulated epidemics discloses the effect of small‐world networks on epidemic propagation as well as the effectiveness of different intervention strategies, including mass vaccination, acquaintance vaccination, targeted vaccination, and contact tracing. Epidemics taking place on small‐world networks tend to reach large‐scale epidemic peaks within a short time period. Among the four intervention strategies tested, only one strategy—the targeted vaccination—proves to be effective for containing epidemics, a finding supported by a simulation of the severe acute respiratory syndrome epidemic in a large‐scale realistic social contact network in Portland, OR.