Antibody status and cumulative incidence of SARS-CoV-2 infection among adults in three regions of France following the first lockdown and associated risk factors: a multicohort study. (19th July 2021)

• Record Type: Journal Article
• Authors: Carrat, Fabrice; de Lamballerie, Xavier; Rahib, Delphine; Blanché, Hélène; Lapidus, Nathanael; Artaud, Fanny; Kab, Sofiane; Renuy, Adeline; Szabo de Edelenyi, Fabien; Meyer, Laurence; Lydié, Nathalie; Charles, Marie-Aline; Ancel, Pierre-Yves; Jusot, Florence; Rouquette, Alexandra; Priet, Stéphane; Saba Villarroel, Paola Mariela; 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
• Is Part Of: International journal of epidemiology. Volume 50:Number 5(2021)
• Page Start: 1458
• Page End: 1472
• Publication Date: 2021-07-19
• Subjects: SARS-CoV-2 -- COVID-19 -- general population -- cohort -- seroprevalence -- risk factors; Epidemiology -- Periodicals; 614.4
• DOI: 10.1093/ije/dyab110
• Languages: English
• ISSNs: 0300-5771

Abstract

Abstract: 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 <40 vs 50–60 years old and OR = 0.56 (95% CI: 0.42, 0.74) in ≥70 vs 50–60 years old)] and when at least one child or adolescent lived in the same household [OR = 1.30 (95% CI: 1.11, 1.53)] and was lower in smokers compared with non-smokers [OR = 0.71 (95% CI: 0.57, 0.89)]. Conclusions: Seropositivity to anti-SARS-CoV-2 antibodies in the French adult population was ≤10% after the first wave. Modifiable and non-modifiable risk factors were identified.