Quantifying hospital flows and occupancy due to COVID-19 outbreak in France. Was French lockdown effective?

Context The spread of SARS-CoV-2 led to a rapid and deadly pandemic which reached almost all countries in the world in a few months. In most countries, rigorous measures of mitigation, including national or subnational lockdowns were established. The present work aimed at quantifying the effect of national lockdown in France on hospital occupancy. Methods A compartmental model describing patient hospital flows was developed, where the effect of lockdown was quantified on the hospitalization rate. Model parameters were estimated using nonlinear mixed-effects (NLME) modelling. Results French lockdown led to a hospitalization rate decreased by thrice from 12 days after its beginning. However, lockdown may not to have decreased either hospital occupancy or deaths in hospital, which would have been both decreased by 30% and 85% in average if lockdown was started 20 and 30 days before this date, respectively. Conclusion The present work showed an intrinsic effect of lockdown to decrease hospital burden, but its efficacy on hospital burden may have been increased if established sooner.