Risk-mediated dynamic regulation of effective contacts de-synchronizes outbreaks in metapopulation epidemic models

TL;DR

This study models how risk-based contact regulation, informed by regional or national data, can influence the spread of epidemics in interconnected communities, highlighting different outcomes based on the level of contact reduction and regional information.

Contribution

It introduces a feedback-based epidemic model that incorporates spatial information to analyze contact reduction strategies and their effects on outbreak dynamics.

Findings

Moderate contact reduction delays and flattens infection waves.

Regional information impacts the effectiveness of mitigation versus suppression.

Desynchronizing local outbreaks helps prevent healthcare system overloads.

Abstract

Metapopulation epidemic models help capture the spatial dimension of infectious disease spread by dividing heterogeneous populations into separate but interconnected communities, represented by nodes in a network. In the event of an epidemic, an important research question is, to what degree spatial information (i.e., regional or national) is relevant for mitigation and (local) policymakers. This study investigates the impact of different levels of information on nationwide epidemic outcomes, modeling the reaction to the measured hazard as a feedback loop reducing contact rates in a metapopulation model based on ordinary differential equations (ODEs). Using COVID-19 and high-resolution mobility data for Germany of 2020 as a case study, we found two markedly different regimes depending on the maximum contact reduction $\psi_{\rm max}$: mitigation and suppression. In the regime of (modest) mitigation, gradually increasing $\psi_{\rm max}$ from zero to moderate levels delayed and spread out the onset of infection waves while gradually reducing the peak values. This effect was more pronounced when the contribution of regional information was low relative to national data. In the suppression regime, the feedback-induced contact reduction is strong enough to extinguish local outbreaks and decrease the mean and variance of the peak day distribution, thus regional information was more important. When suppression or elimination is impossible, ensuring local epidemics are desynchronized helps to avoid hospitalization or intensive care bottlenecks by reallocating resources from less-affected areas.