Modelling the Evolution of COVID-19 in High-Incidence European Countries and Regions: Estimated Number of Infections and Impact of Past and Future Intervention Measures.

Juan Fernández-Recio

doi:10.3390/jcm9061825

Abstract

A previously developed mechanistic model of COVID-19 transmission has been adapted and applied here to study the evolution of the disease and the effect of intervention measures in some European countries and territories where the disease has had a major impact. A clear impact of the major intervention measures on the reproduction number (Rt) has been found in all studied countries and territories, as already suggested by the drop in the number of deaths over time. Interestingly, the impact of such major intervention measures seems to be the same in most of these countries. The model has also provided realistic estimates of the total number of infections, active cases and future outcomes. While the predictive capabilities of the model are much more uncertain before the peak of the outbreak, we could still reliably predict the evolution of the disease after a major intervention by assuming the subsequent reproduction number from the current study. A greater challenge is to foresee the long-term impact of softer intervention measures, but this model can estimate the outcome of different scenarios and help to plan changes for the implementation of control measures in a given country or region.

Highlights

The ongoing pandemic expansion of the new SARS-CoV-2 virus has caused over 3,500,000 detected cases of coronavirus disease 2019 (COVID-19) and claimed over 240,000 lives worldwide as of 5 May 2020 [1]
A recent model of SARS-CoV-2 transmission based on estimates of seasonality, immunity and cross-immunity from past virus pandemic data indicates the high risk of recurrent outbreaks in the coming years, according to different scenarios [2]
A major problem is that in most countries, only a small portion of the infected individuals is detected, and as a consequence, undetected contagious patients are the major cause of the expansion of the disease, which is the main limitation in foreseeing the effect of intervention measures

Summary

Introduction

The ongoing pandemic expansion of the new SARS-CoV-2 virus has caused over 3,500,000 detected cases of coronavirus disease 2019 (COVID-19) and claimed over 240,000 lives worldwide as of 5 May 2020 [1]. Strict social distancing enforced by the authorities has been the strategy of choice by the majority of countries in this first epidemic outbreak, implemented as different measures in each country (imposing or encouraging home confinement, closing schools and workplaces and banning assemblies and gatherings, among others). Given that this usually involves a strong economic and behavioral impact in a society, it is urgently necessary to understand the evolution of the disease in each country or territory and to estimate the effect of implementing such control measures. The specific impact of the different control measures was difficult to analyze at that time

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Conclusion