BACKGROUND: We aimed to estimate the seropositivity to anti-SARS-CoV-2 antibodies in May-June 2020 after the first lockdown period in adults living in three regions in France and to identify the associated risk factors. METHODS: Between 4 May 2020 and 23 June 2020, 16 000 participants in a survey on COVID-19 from an existing consortium of three general adult population cohorts living in the Ile-de-France (IDF) or Grand Est (GE) (two regions with high rate of COVID-19) or in the Nouvelle-Aquitaine (NA) (with a low rate) were randomly selected to take a dried-blood spot for anti-SARS-CoV-2 antibodies assessment with three different serological methods (ClinicalTrial Identifier #NCT04392388). The primary outcome was a positive anti-SARS-CoV-2 ELISA IgG result against the spike protein of the virus (ELISA-S). Estimates were adjusted using sampling weights and post-stratification methods. Multiple imputation was used to infer the cumulative incidence of SARS-CoV-2 infection with adjustments for imperfect tests accuracies. RESULTS: The analysis included 14 628 participants, 983 with a positive ELISA-S. The weighted estimates of seropositivity and cumulative incidence were 10.0% [95% confidence interval (CI): 9.1%, 10.9%] and 11.4% (95% CI: 10.1%, 12.8%) in IDF, 9.0% (95% CI: 7.7%, 10.2%) and 9.8% (95% CI: 8.1%, 11.8%) in GE and 3.1% (95% CI: 2.4%, 3.7%) and 2.9% (95% CI: 2.1%, 3.8%) in NA, respectively. Seropositivity was higher in younger participants [odds ratio (OR)?=?1.84 (95% CI: 1.79, 6.09) in
Auteur : Carrat Fabrice, de Lamballerie Xavier, Rahib Delphine, Blanché Hélène, Lapidus Nathanael, Artaud Fanny, Kab Sofiane, Renuy Adeline, de Edelenyi Fabien Szabo, Meyer Laurence, Lydié Nathalie, Charles Marie-Aline, Ancel Pierre-Yves, Jusot Florence, Rouquette Alexandra, Priet Stéphane, Villarroel Paola Mariela Saba, Fourié Toscane, Lusivika-Nzinga Clovis, Nicol Jérôme, Legot Stephane, Druesne-Pecollo Nathalie, Esseddik Younes, Lai Cindy, Gagliolo Jean-Marie, Deleuze Jean-François, Bajos Nathalie, Severi Gianluca, Touvier Mathilde, Zins Marie
International journal of epidemiology, 2021, vol. 50, n°. 5, p. 1458-1472