Pierre Charneau, Philippe Souque, Evelyne Dufour, Marion Gransagne, Stéphane Petres, Ana Ines Lalanne, Thierry Rose, Isabelle Turbiez, François Dejardin, François Anna, Odile Richard-Le Goff, Olivier Helynck, Maude Guillot-Delost, Sophie Goyard, Alexia Savignoni, François-Clément Bidard, Zaineb Choucha, Fabien Nevo, Franck Perez, Delphine Louis, Véronique Gillon, Yves L. Janin, A Gobillion, Nicolas Escriou, Olivier Lantz, Laboratoire commun Pasteur-TheraVectys, Institut Pasteur [Paris]-TheraVectys, Biologie Cellulaire des Lymphocytes - Lymphocyte Cell Biology, Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut Pasteur [Paris], Institut Curie [Paris], Virologie Moléculaire et Vaccinologie / Molecular Virology and Vaccinology, Institut Pasteur [Paris], Laboratoire d’innovation : vaccins – Innovation lab : vaccines, Risques cliniques et sécurité en santé des femmes et en santé périnatale (RISCQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Immunité et cancer (U932), Institut Curie [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP), Plateforme technologique Production et purification de protéines recombinantes – Production and Purification of Recombinant Proteins Technological Platform (PPR), Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Anticorps en thérapie et pathologie - Antibodies in Therapy and Pathology, Chimie et Biocatalyse, This work was made possible thanks to the financial support obtained through the URGENCE nouveau coronavirus fundraising campaign of Institut Pasteur and the financial support of the Fondation Total. This study was funded in part by a grant from Fondation de France and by Institut Curie Institutional funding. The luciferin synthesis development has been supported by DARRI (ValoExpress 2016-2018). LuLISA development has been supported by IARP Pasteur-Carnot MI (2019-2020)., Institut Pasteur [Paris] (IP)-TheraVectys, Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut Pasteur [Paris] (IP), Université Paris-Saclay, Institut Curie [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), Lassailly-Bondaz, Anne, Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut Curie [Paris], Institut Pasteur [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM), and Centre National de la Recherche Scientifique (CNRS)-Institut Pasteur [Paris]
International audience; Background Although the COVID-19 pandemic peaked in March/April 2020 in France, the prevalence of infection is barely known. Herein, we assessed the serological response against the SARS-CoV-2 virus in a large population working in one institution of the Paris conurbation. We set up two high-throughput and sensitive methods to assess SARS CoV-2 Nucleoprotein and Spike protein-specific IgG response along with a pseudo-neutralization assay in sera. We studied 1847 participants who also answered a web-based survey on clinical symptoms.Methods and Results In May-July 2020, 11% (95% CI: 9.7-12.6) of serums were positive for IgG against the SARS-CoV-2 N and S protein and 9.5% (CI:8.2-11.0) were pseudo-neutralizer. The prevalence of immunization was 11.6% (CI:10.2-13.2) considering positivity in at least one assays. In 5% (CI:3.9-7.1) of RT-qPCR positive individuals, no systemic IgGs were detected. Among immune individuals, 21% had been asymptomatic.Anosmia and ageusia occurred in 52% of the IgG-positive individuals and in 3% of the negative ones. In contrast, 30% of the anosmia-ageusia cases were seronegative suggesting that the true prevalence of infection may reach 16.6%. In sera obtained 4-8 weeks after the first sampling anti-N and anti-S IgG titers and pseudo-neutralization activity declined by 31%, 17% and 53%, respectively with half-life of 35, 87 and 28 days, respectively.Conclusions The population studied being not particularly exposed to SARS-CoV-2 infection is representative of active workers in the Paris conurbation, suggesting that the current epidemiological models may underestimate the true prevalence of infection. The short lifespan of the serological systemic responses hinders retrospective assessment of the epidemic extent.