Cluster of COVID-19 in northern France: A retrospective closed cohort study

Archive ouverte

Fontanet, Arnaud | Tondeur, Laura | Madec, Yoann | Grant, Rebecca | Besombes, Camille | Jolly, Nathalie | Pellerin, Sandrine Fernandes | Ungeheuer, Marie-Noëlle | Cailleau, Isabelle | Kuhmel, Lucie | Temmam, Sarah | Huon, Christèle | Chen, Kuang-Yu | Crescenzo, Bernadette | Munier, Sandie | Demeret, Caroline | Grzelak, Ludivine | Staropoli, Isabelle | Bruel, Timothée | Gallian, Pierre | Cauchemez, Simon | van Der Werf, Sylvie | Schwartz, Olivier | Eloit, Marc | Hoen, Bruno

Edité par CCSD -

Posté sur MedRxiv le 23 avril 2020. Background: The Oise department in France has been heavily affected by COVID-19 in early 2020.Methods: Between 30 March and 4 April 2020, we conducted a retrospective closed cohort study amongpupils, their parents and siblings, as well as teachers and non-teaching staff of a high-school located inOise. Participants completed a questionnaire that covered history of fever and/or respiratory symptomssince 13 January 2020 and had blood tested for the presence of anti-SARS-CoV-2 antibodies. Theinfection attack rate (IAR) was defined as the proportion of participants with confirmed SARS-CoV-2infection based on antibody detection. Blood samples from two blood donor centres collected between23 and 27 March 2020 in the Oise department were also tested for presence of anti-SARS-CoV-2antibodies.Findings: Of the 661 participants (median age: 37 years), 171 participants had anti-SARS-CoV-2antibodies. The overall IAR was 25.9% (95% confidence interval (CI) = 22.6-29.4), and the infectionfatality rate was 0% (one-sided 97.5% CI = 0 - 2.1). Nine of the ten participants hospitalised since midJanuary were in the infected group, giving a hospitalisation rate of 5.3% (95% CI = 2.4 –9.8). Anosmia and ageusia had high positive predictive values for SARS-CoV-2 infection (84.7% and 88.1%,respectively). Smokers had a lower IAR compared to non-smokers (7.2% versus 28.0%, P <0.001). Theproportion of infected individuals who had no symptoms during the study period was 17.0% (95% CI =11.2 – 23.4). The proportion of donors with anti-SARS-CoV-2 antibodies in two nearby blood banksof the Oise department was 3.0% (95% CI = 1.1 - 6.4).Interpretation: The relatively low IAR observed in an area where SARS-CoV-2 actively circulatedweeks before confinement measures indicates that establishing herd immunity will take time, and thatlifting these measures in France will be long and complex.

• Description
• Sujet/Public
• Outil
• Outil d'anticipation
• Mémoire et thèse
• Gestion