SARS-CoV-2 IgG seroprevalence surveys in blood donors before the vaccination campaign, France 2020-2021

Pierre Gallian (1, 2) , Nathanaël Hozé (3) , Nadège Brisbarre (2, 4) , Paola Mariela Saba Villarroel (2) , Elif Nurtop (2) , Christine Isnard (2, 4) , Boris Pastorino (2) , Pascale Richard (1) , Pascal Morel (1, 5) , Simon Cauchemez (3) , Xavier de Lamballerie (2)

1 EFS - Etablissement Français du Sang [La Plaine Saint-Denis]
2 UVE - Unité des Virus Emergents
3 Modélisation mathématique des maladies infectieuses - Mathematical modelling of Infectious Diseases
4 EFS - Etablissement Français du Sang Provence-Alpes Côte-d'Azur et Corse
5 RIGHT - Interactions hôte-greffon-tumeur, ingénierie cellulaire et génique - UFC (UMR INSERM 1098)

We conducted a cross-sectional study for SARS-CoV-2 anti-S1 IgG prevalence in French blood donors (n=32605), from March-2020 to January-2021. A mathematical model combined seroprevalence with daily number of hospital admissions to estimate the probability of hospitalization upon infection and determine the number of infections while correcting for antibody decay. There was an overall seroprevalence increase over the study period and we estimate that ∼15% of the French population had been infected by SARS-CoV-2 by January-2021. The infection/hospitalization ratio increased with age, from 0.31% (18-30yo) to 4.5% (61-70yo). Half of the IgG-S1 positive individuals had no detectable antibodies 4 to 5 months after infection. The seroprevalence in group O donors (7.43%) was lower (p=0.003) than in A, B and AB donors (8.90%). We conclude, based on seroprevalence data and mathematical modelling, that a large proportion of the French population was unprotected against severe disease prior to the vaccination campaign.

Mots clés: Immune response; Immunology; Virology

Domaines: Sciences du Vivant [q-bio]; Vaccinologie; Virologie

Pierre Gallian, Nathanaël Hozé, Nadège Brisbarre, Paola Mariela Saba Villarroel, Elif Nurtop, et al.. SARS-CoV-2 IgG seroprevalence surveys in blood donors before the vaccination campaign, France 2020-2021. iScience, 2023, 26 (4), pp.106222. ⟨10.1016/j.isci.2023.106222⟩. ⟨hal-04007375⟩