Estimating the burden of SARS-CoV-2 in France

TLDR

France was heavily affected by SARS‑CoV‑2 and entered lockdown on 17 March 2020. The study estimates the impact of lockdown and current population immunity. Models applied to hospital and death data were used to make these estimates. The analysis shows that 2.9 % of infected individuals were hospitalized and 0.5 % died, with higher rates in older age groups and men, a 77 % reduction in the reproductive number to 0.67, and that by 11 May 2020 approximately 5.3 % of the population would have been infected, indicating insufficient immunity to prevent a second wave.

Abstract

France has been heavily affected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and went into lockdown on 17 March 2020. Using models applied to hospital and death data, we estimate the impact of the lockdown and current population immunity. We find that 2.9% of infected individuals are hospitalized and 0.5% of those infected die (95% credible interval: 0.3 to 0.9%), ranging from 0.001% in those under 20 years of age to 8.3% in those 80 years of age or older. Across all ages, men are more likely to be hospitalized, enter intensive care, and die than women. The lockdown reduced the reproductive number from 2.90 to 0.67 (77% reduction). By 11 May 2020, when interventions are scheduled to be eased, we project that 3.5 million people (range: 2.1 million to 6.0 million), or 5.3% of the population (range: 3.3 to 9.3%), will have been infected. Population immunity appears to be insufficient to avoid a second wave if all control measures are released at the end of the lockdown.