Topological Properties of the Effective Reproduction Number in an Heterogeneous SIS Model

Fuente: arXiv
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Main Authors: Delmas, Jean-François, Dronnier, Dylan, Zitt, Pierre-André
Format: Preprint
Published: 2025
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author Delmas, Jean-François
Dronnier, Dylan
Zitt, Pierre-André
author_facet Delmas, Jean-François
Dronnier, Dylan
Zitt, Pierre-André
contents This present results lay the foundations for the study of the optimal allocation of vaccine in the simple epidemiological SIS model where one consider a very general heterogeneous population. In the present setting each individual has a type x belonging to a general space, and a vaccination strategy is a function $η$ where $η$(x) $\in$ [0, 1] represents the proportion of non-vaccinated among individuals of type x. We shall consider two loss functions associated to a vaccination strategy $η$: either the effective reproduction number, a classical quantity appearing in many models in epidemiology, and which is given here by the spectral radius of a compact operator that depends on $η$; or the overall proportion of infected individuals after vaccination in the maximal endemic state.By considering the weak-* topology on the set $Δ$ of vaccination strategies, so that it is a compact set, we can prove that those two loss functions are continuous using the notion of collective compactness for a family of operators. We also prove their stability with respect to the parameters of the SIS model. Eventually, we consider their monotonicity and related properties in particular when the model is ``almost'' irreducible.
format Preprint
id arxiv_https___arxiv_org_abs_2504_00055
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Topological Properties of the Effective Reproduction Number in an Heterogeneous SIS Model
Delmas, Jean-François
Dronnier, Dylan
Zitt, Pierre-André
Populations and Evolution
Functional Analysis
This present results lay the foundations for the study of the optimal allocation of vaccine in the simple epidemiological SIS model where one consider a very general heterogeneous population. In the present setting each individual has a type x belonging to a general space, and a vaccination strategy is a function $η$ where $η$(x) $\in$ [0, 1] represents the proportion of non-vaccinated among individuals of type x. We shall consider two loss functions associated to a vaccination strategy $η$: either the effective reproduction number, a classical quantity appearing in many models in epidemiology, and which is given here by the spectral radius of a compact operator that depends on $η$; or the overall proportion of infected individuals after vaccination in the maximal endemic state.By considering the weak-* topology on the set $Δ$ of vaccination strategies, so that it is a compact set, we can prove that those two loss functions are continuous using the notion of collective compactness for a family of operators. We also prove their stability with respect to the parameters of the SIS model. Eventually, we consider their monotonicity and related properties in particular when the model is ``almost'' irreducible.
title Topological Properties of the Effective Reproduction Number in an Heterogeneous SIS Model
topic Populations and Evolution
Functional Analysis
url https://arxiv.org/abs/2504.00055