Detection of SARS-CoV-2 antibodies using commercial assays and seroconversion patterns in hospitalized patients

• Published in: The Journal of infection Vol. 81; no. 2; pp. e39 - e45
• Main Authors: Tuaillon, E, Bolloré, K, Pisoni, A, Debiesse, S, Renault, C, Marie, S, Groc, S, Niels, C, Pansu, N, Dupuy, AM, Morquin, D, Foulongne, V, Bourdin, A, Le Moing, V, Van de Perre, P
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2020; Elsevier; The British Infection Association. Published by Elsevier Ltd
• Subjects: Adaptive immunology; Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Viral - blood; Betacoronavirus - immunology; Clinical Laboratory Techniques; Coronavirus Infections - diagnosis; Coronavirus Infections - immunology; COVID-19; COVID-19 Testing; ELISA; Enzyme-Linked Immunosorbent Assay; Female; Hospitalization - statistics & numerical data; Human health and pathology; Humans; Immunology; Infectious diseases; Life Sciences; Male; Middle Aged; Pandemics; Pneumonia, Viral - diagnosis; Pneumonia, Viral - immunology; point of care tests; Point-of-Care Systems; Reagent Kits, Diagnostic; SARS-CoV-2; SARS-CoV-2 antibodies; Sensitivity and Specificity; Seroconversion; Serologic Tests; Young Adult; COVID-19; SARS-CoV-2 antibodies; point of care tests; ELISA
• ISSN: 0163-4453; 1532-2742; 1532-2742
• DOI: 10.1016/j.jinf.2020.05.077

SARS-CoV-2 antibody assays are needed for serological surveys and as a complement to molecular tests to confirm COVID-19. However, the kinetics of the humoral response against SARS-CoV-2 remains poorly described and relies on the performance of the different serological tests. In this study, we evaluated the performance of six CE-marked point-of-care tests (POC) and three ELISA assays for the diagnosis of COVID-19 by exploring seroconversions in hospitalized patients who tested positive for SARS-CoV-2 RNA. Both the ELISA and POC tests were able to detect SARS-CoV-2 antibodies in at least half of the samples collected seven days or more after the onset of symptoms. After 15 days, the rate of detection rose to over 80% but without reaching 100%, irrespective of the test used. More than 90% of the samples collected after 15 days tested positive using the iSIA and Accu-Tell® POC tests and the ID.Vet IgG ELISA assay. Seroconversion was observed 5 to 12 days after the onset of symptoms. Three assays suffer from a specificity below 90% (EUROIMMUN IgG and IgA, UNscience, Zhuhai Livzon). The second week of COVID-19 seems to be the best period for assessing the sensitivity of commercial serological assays. To achieve an early diagnosis of COVID-19 based on antibody detection, a dual challenge must be met: the immunodiagnostic window period must be shortened and an optimal specificity must be conserved.