Impact of lockdown on COVID-19 epidemic in Île-de-France and possible exit strategies

3 September 2020

The French National Institute of Health and Medical Research (INSERM) and Sociology and Economics of Networks and Services lab at Orange Experience Design Lab published a RECOVER co-funded paper on the impact of lockdown on COVID-19 epidemic in Île-de-France and possible exit strategies.

This modeling study uses at mathematical model to

  1. Assess the current COVID-19 pandemic situation in France
  2. Evaluate the impact of the lockdown implemented nationwide on March 17, 2020
  3. Estimate the effectiveness of possible exit strategies.

French government implemented a nationwide lockdown from March 17 up to May 11 2020 in order to curb the spread of COVID-19. This measure slowed the incidence of clinical cases and transmissibility per contact. The study looks at different measures that could be implemented after lifting the lockdown in to substantially delay and mitigate the epidemic.

Further relaxing social distancing constraints would be possible by progressively going through decreasing levels of intensity of interventions while maintaining highly efficient tracing. Alternatively, strict and mild interventions can be rotated every month if case isolation capacity is less efficient. All exit strategies would be able to maintain the epidemic under control in the upcoming months if a larger proportion of infected individuals are asymptomatic. 

Exit strategies however exist that would maintain the epidemic under control. Also, changes in the risk of transmission from younger children would lead to similar results. If individuals continue to avoid all physical contacts in the next months, all exit strategies considered here foresee the suppression of the epidemic in the region.

The original version of this study was made available as a preprint in mid-April, 1 month before the exit from lockdown. This revised version updates the comparison and validation of model projections, once data became available, while maintaining the context of the beginning of lockdown.

Read article here.

Authors: Laura Di Domenico, Giulia Pullano, Chiara E. Sabbatini, Pierre-Yves Boëlle & Vittoria Colizza

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