On the Endemic Behavior of a Competitive Tri-Virus SIS Networked Model

TL;DR

This paper analyzes the complex endemic behaviors of a three-virus SIS network model, revealing conditions for virus extinction, coexistence, and convergence to equilibrium states, highlighting the system's non-monotonic nature.

Contribution

It provides new conditions for convergence to boundary and coexistence equilibria in a tri-virus SIS model, extending understanding of multi-virus epidemic dynamics.

Findings

System is non-monotone.

Conditions for local exponential convergence to boundary equilibrium.

Existence of a line and plane of coexistence equilibria.

Abstract

This paper studies the endemic behavior of a multi-competitive networked susceptible-infected-susceptible (SIS) model. In particular, we focus on the case where there are three competing viruses (i.e., the tri-virus system). First, we show that the tri-virus system is not a monotone system. Thereafter, we provide a condition that guarantees local exponential convergence to a boundary equilibrium (exactly one virus is endemic, the other two are dead), and identify a special case that admits the existence and local exponential attractivity of a line of coexistence equilibria (at least two viruses are active). Finally, we identify a particular case (subsumed by the aforementioned special case) such that, for all nonzero initial infection levels, the dynamics of the tri-virus system converge to a plane of coexistence equilibria.