Hospital and Population-Based Evidences for COVID-19 Early Circulation in the East of France

Background: Understanding the SARS-CoV-2 dynamics and transmission is a major issue to model and control its propagation. The Alsace region in the East of France has been among the first French COVID-19 clusters in 2020. Methods: We confront evidences from three independent and retrospective sources: a population-based survey through internet, an analysis of the medical records from hospital emergency care services and the review of medical biology laboratory data. We also check the role played in the virus propagation by a large religious meeting which gathered over 2000 participants from all over France mid-February in Mulhouse. Results: SARS-CoV-2 was circulating several weeks before the first officially recognized case in Alsace on February 26th 2020 and the sanitary alert on March 3rd. The religious gathering played a role for secondary dissemination of the epidemic in France, but not in creating the local outbreak which was in place much earlier. Conclusions: Our results illustrate how the integration of data coming from multiple sources could help trigger an early alarm in the context of an emerging disease. Good information data systems, able to produce earlier alerts, could have avoided a general lockdown in France.