Lockdowns have been used by most European countries in response to the COVID-19 pandemic. In France, a national lockdown was implemented on March 17, 2020. Some have questioned the need for a nationwide implementation given that most hospital admissions were concentrated in two of 13 regions; others have even questioned the impact of the lockdown on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread, arguing that the natural epidemic peak was about to be reached. Here we discuss the impact of lockdown on COVID-19 epidemics in regions across metropolitan France.

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 hos­pital 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.