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

• Published in: iScience Vol. 26; no. 4; p. 106222
• Main Authors: Gallian, Pierre, Hozé, Nathanaël, Brisbarre, Nadège, Saba Villarroel, Paola Mariela, Nurtop, Elif, Isnard, Christine, Pastorino, Boris, Richard, Pascale, Morel, Pascal, Cauchemez, Simon, de Lamballerie, Xavier
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.04.2023; Elsevier; The Author(s)
• Subjects: Immune response; Immunology; Life Sciences; Microbiology and Parasitology; Vaccinology; Virology; Immunology; Immune response; Virology
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2023.106222

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 a 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 modeling, that a large proportion of the French population was unprotected against severe disease prior to the vaccination campaign. [Display omitted] •Immunity in France before the vaccination campaign was too low to achieve herd immunity•The infection/hospitalization ratio increased with age•4 months after seroconversion, modeling estimated antibody decay to be ∼50%•IgG seroprevalence was lower in individuals with O blood type than A, B, and AB Immunology; Immune response; Virology