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Main Authors: Chowdhury, Sourav, Bose, Indrani, Roychowdhury, Suparna, Chaudhuri, Indranath
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.01310
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author Chowdhury, Sourav
Bose, Indrani
Roychowdhury, Suparna
Chaudhuri, Indranath
author_facet Chowdhury, Sourav
Bose, Indrani
Roychowdhury, Suparna
Chaudhuri, Indranath
contents In this paper, we study a stochastic susceptible-infected-susceptible (SIS) epidemic model that includes an additional immigration process. In the presence of multiplicative noise, generated by environmental perturbations, the model exhibits noise-induced transitions. The bifurcation diagram has two distinct regions of unimodality and bimodality in which the steady-state probability distribution has one and two peaks, respectively. Apart from first-order transitions between the two regimes, a critical-point transition occurs at a cusp point with the transition belonging to the mean-field Ising universality class. The epidemic model shares these features with the well-known Horsthemke-Lefever model of population genetics. The effect of vaccination on the spread/containment of the epidemic in a stochastic setting is also studied. We further propose a general vaccine-hesitancy model, along the lines of Kirman's ant model, with the steady-state distribution of the fraction of the vaccine-willing population given by the Beta distribution. The distribution is shown to give a good fit to the COVID-19 data on vaccine hesitancy and vaccination. We derive the steady-state probability distribution of the basic reproduction number, a key parameter in epidemiology, based on a beta-distributed fraction of the vaccinated population. Our study highlights the universal features that epidemic and vaccine models share with other dynamical models.
format Preprint
id arxiv_https___arxiv_org_abs_2507_01310
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Universal features of epidemic and vaccine models
Chowdhury, Sourav
Bose, Indrani
Roychowdhury, Suparna
Chaudhuri, Indranath
Populations and Evolution
Biological Physics
In this paper, we study a stochastic susceptible-infected-susceptible (SIS) epidemic model that includes an additional immigration process. In the presence of multiplicative noise, generated by environmental perturbations, the model exhibits noise-induced transitions. The bifurcation diagram has two distinct regions of unimodality and bimodality in which the steady-state probability distribution has one and two peaks, respectively. Apart from first-order transitions between the two regimes, a critical-point transition occurs at a cusp point with the transition belonging to the mean-field Ising universality class. The epidemic model shares these features with the well-known Horsthemke-Lefever model of population genetics. The effect of vaccination on the spread/containment of the epidemic in a stochastic setting is also studied. We further propose a general vaccine-hesitancy model, along the lines of Kirman's ant model, with the steady-state distribution of the fraction of the vaccine-willing population given by the Beta distribution. The distribution is shown to give a good fit to the COVID-19 data on vaccine hesitancy and vaccination. We derive the steady-state probability distribution of the basic reproduction number, a key parameter in epidemiology, based on a beta-distributed fraction of the vaccinated population. Our study highlights the universal features that epidemic and vaccine models share with other dynamical models.
title Universal features of epidemic and vaccine models
topic Populations and Evolution
Biological Physics
url https://arxiv.org/abs/2507.01310