Qualitative Properties of Solutions to Nonlocal Infectious SIR Epidemic Models

ABSTRACT This paper studies qualitative properties of solutions of nonlocal infectious SIR epidemic models (1.3)–(1.5), with the homogeneous Neumann boundary conditions, Dirichlet boundary conditions, and free boundary, respectively. We first use the upper and lower solutions method and the Lyapunov function method to prove the global asymptotically stabilities of the disease‐free equilibrium and the unique positive equilibrium of (1.3). Then we use the theory of topological degree in cones to study the positive equilibrium solutions of (1.4), including the necessary and sufficient conditions for the existence, and the uniqueness in some special case. At last, for the free boundary problem (1.5), we study the longtime behaviors of solutions and criteria for spreading and vanishing. The highlights are to overcome failures of the Lyapunov functional method and the comparison principle, and difficulties in the maximum principle and Hopf boundary lemma of boundary value problems caused by nonlocal terms.