key: cord-0804196-xygvsr8i
authors: Cauchemez, Simon; Kiem, Cécile Tran; Paireau, Juliette; Rolland, Patrick; Fontanet, Arnaud
title: Lockdown impact on COVID-19 epidemics in regions across metropolitan France
date: 2020-09-29
journal: Lancet
DOI: 10.1016/s0140-6736(20)32034-1
sha: ad00fb3c739071d9196a696adcae05642a94401d
doc_id: 804196
cord_uid: xygvsr8i

nan

On March 17, 2020, daily hospital admissions were indeed highest in Grand-Est (5·3 per 100 000 inhabitants) and Île-de-France (3·6 per 100 000 inhabitants) regions. Yet a surge in COVID-19 hospital admissions was occurring at that time across all regions of metropolitan France, as depicted in the appendix. The COVID-19 epidemic spread from the eastern to the western parts of France, crossing the daily hospitalisation threshold of 1 per 100 000 inhabitants between March 10 (Grand-Est) and March 23, 2020 (Bretagne and Nouvelle-Aquitaine). Île-de-France (Paris region) experienced the highest rate of hos pital admissions per day (10·0 per 100 000 inhabitants), and Bretagne the lowest (1·3 per 100 000 inhabitants). Regardless of the time the epidemic started in the region, and its scale, 12 of 13 regions experienced a peak in daily hospital admissions on average 11 days (range 8-14 days) after the lockdown was implemented. This figure corresponds to the mean duration between infection and hospital admission for the patients experiencing severe forms of disease. 1 Since the different regions were at different stages of the pandemic at the time the lockdown was imple mented, the synchrony in regional peaks strongly suggests that the lockdown, rather than the natural course of the epidemic, explains the peak in hospital admissions. Moreover, most regions were experiencing exponential growth in hospital admissions (appendix), such that saturation of local intensive care units might have occurred in those regions in the absence of any lockdown.

Lockdown therefore appears to have been successful not only in alleviating the burden on the intensive care units of the two most severely affected regions of France, but also in preventing uncontrolled epidemics in other regions. These simple observations support results from other studies which have estimated the impact of lockdown on SARS-CoV-2 spread to be strong. [2] [3] [4] [5] Enforcement of public health and social measures in combination with important testing, tracing, and isolating capacities will be critical in case of an epidemic rebound to avoid re-introducing a lockdown-a situation for which the economic cost and broader impact on society are considerable. 

Mathematical Modelling of Infectious Diseases Unit

Epidemiology of Emerging Diseases Unit

Conservatoire National des Arts et Métiers

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See Online for appendix