Compounded individual contact heterogeneity facilitates infectious disease spread on metapopulation networks

Studies on SIS-type infectious diseases coupled with individual contact heterogeneity on metapopulation networks have revealed the dual role of such heterogeneity in disease transmission. However, the impact of individual contact heterogeneity on metapopulation networks on the transmission dynamics of SIR-type diseases remains unclear. To address this, we construct an SIR infectious disease model, coupling inter-subpopulation individual mobility with intra-subpopulation individual contact heterogeneity. We calculate the theoretical equilibria, basic reproduction number R0, and final size. Through simulations, we find that the compounding of the initial individual contact heterogeneity within subpopulations at the starting time and the heterogeneity introduced by immigrating individuals significantly accelerates the infectious disease transmission process. This compounded effect leads to an earlier peak time, a higher peak prevalence, and a larger final size. Conversely, if individual contacts within initial subpopulations are homogeneous, heterogeneity induced by individual mobility can surprisingly suppress infectious disease spread. In addition, the impact of the mobility rate on infectious disease transmission shifts from promoting to suppressing as the mobility rate increases. Moreover, we find that when R0>1, the final size reaches 100%, which breaks with the conclusion of a final size strictly less than 100% in the traditional deterministic SIR model. This study advances the theoretical framework of how individual contact heterogeneity influences infectious disease transmission on metapopulation networks and provides a critical foundation for developing targeted control strategies for SIR-type infectious diseases.