Endemic infectious states below the epidemic threshold and beyond herd immunity

Fuente: arXiv
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Autori principali: Aguilar, Javier, García, Beatriz Arregui, Toral, Raúl, Meloni, Sandro, Ramasco, Jose J.
Natura: Preprint
Pubblicazione: 2022
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author Aguilar, Javier
García, Beatriz Arregui
Toral, Raúl
Meloni, Sandro
Ramasco, Jose J.
author_facet Aguilar, Javier
García, Beatriz Arregui
Toral, Raúl
Meloni, Sandro
Ramasco, Jose J.
contents In the recent COVID-19 pandemic we assisted at a sequence of epidemic waves intertwined by anomalous fade-outs with periods of low but persistent epidemic prevalence. These long-living epidemic states complicate epidemic control and challenge current modeling approaches as classical epidemic models fail to explain their emergence. Inspired by this phenomenon, we propose a simple mechanism able to reproduce several features observed in real data. Specifically, here we introduce a modification of the Susceptible-Infected-Recovered (SIR) model in a meta-population framework where a small inflow of infected individuals accounts for undetected internal or imported cases. Focusing on a regime where this external seeding is so small that cannot be detected from the analysis of epidemic curves, we find that outbreaks of finite duration percolate in time resulting in overall low but long-living epidemic states below and above the epidemic threshold. Using a two-state description of the local dynamics, we can extract analytical predictions for the phase space. The comparison with epidemic data demonstrates that our model is able to reproduce some critical signatures observed in COVID-19 spreading in England. Finally, our findings defy our understanding of the concept of epidemic threshold and its relationship with outbreaks survival for disease control.
format Preprint
id arxiv_https___arxiv_org_abs_2207_03462
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Endemic infectious states below the epidemic threshold and beyond herd immunity
Aguilar, Javier
García, Beatriz Arregui
Toral, Raúl
Meloni, Sandro
Ramasco, Jose J.
Physics and Society
Populations and Evolution
In the recent COVID-19 pandemic we assisted at a sequence of epidemic waves intertwined by anomalous fade-outs with periods of low but persistent epidemic prevalence. These long-living epidemic states complicate epidemic control and challenge current modeling approaches as classical epidemic models fail to explain their emergence. Inspired by this phenomenon, we propose a simple mechanism able to reproduce several features observed in real data. Specifically, here we introduce a modification of the Susceptible-Infected-Recovered (SIR) model in a meta-population framework where a small inflow of infected individuals accounts for undetected internal or imported cases. Focusing on a regime where this external seeding is so small that cannot be detected from the analysis of epidemic curves, we find that outbreaks of finite duration percolate in time resulting in overall low but long-living epidemic states below and above the epidemic threshold. Using a two-state description of the local dynamics, we can extract analytical predictions for the phase space. The comparison with epidemic data demonstrates that our model is able to reproduce some critical signatures observed in COVID-19 spreading in England. Finally, our findings defy our understanding of the concept of epidemic threshold and its relationship with outbreaks survival for disease control.
title Endemic infectious states below the epidemic threshold and beyond herd immunity
topic Physics and Society
Populations and Evolution
url https://arxiv.org/abs/2207.03462