Analysis of a Competitive Bivirus SIS Epidemic Model with Game Theoretic Social Distancing
Social distancing behavior can flip which virus dominates or let both coexist.
A new paper from researchers Catalano, Paarporn, and Gracy introduces a competitive bivirus epidemic model that integrates dynamic social distancing behavior driven by game theory. The model treats individuals as rational agents who adjust their distancing efforts based on the perceived severity of each circulating virus. Unlike the classic monotone bivirus models, this framework is non-monotone, leading to richer equilibrium structures—including lines of coexistence equilibria—and fundamentally changing the conditions under which outbreaks persist or die out.
The authors rigorously analyze the system's stability. They derive necessary and sufficient conditions for almost global exponential stability of the disease-free equilibrium (DFE) and prove similar global results for all non-DFE isolated (unilateral) equilibria except one. Local stability conditions are provided for the remainder. The key insight: when social distancing responses differ per virus, the system can support coexistence or dominance patterns not seen in traditional models. Numerical simulations demonstrate these theoretical findings, highlighting practical implications for public health policy during multi-pathogen seasons.
- Model is non-monotone, allowing lines of coexistence equilibria unlike classic bivirus models.
- Public perception of virus severity directly alters stability of disease-free and endemic equilibria.
- Authors prove necessary & sufficient conditions for almost global exponential stability of DFE.
Why It Matters
Informs public health strategy for simultaneous outbreaks by factoring in behavioral responses to perceived risk.