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

E. Tuaillon (1, 2, 3) , K. Bollore (2, 1) , A. Pisoni (1, 2) , S Debiesse (1, 2) , C. Renault (1, 2) , S Marie (1) , S Groc (1) , C Niels (1) , N Pansu (1) , Anne Marie Dupuy (1) , D Morquin (1) , V Foulongne (1, 2) , Arnaud Bourdin (1, 4) , V Le Moing (1) , P van de Perre (1, 2)

1 CHRU Montpellier - Centre Hospitalier Régional Universitaire [Montpellier]
2 Pathogénèse et contrôle des infections chroniques (PCCI)
3 UM - Université de Montpellier
4 PhyMedExp - Physiologie & médecine expérimentale du Cœur et des Muscles [U 1046]

Objectives: 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. Methods: 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. Results: 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). Conclusions: 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.

Mots clés: COVID-19; SARS-CoV-2 antibodies; point of care tests; ELISA

Domaines: Maladies infectieuses; Immunité adaptative

E. Tuaillon, K. Bollore, A. Pisoni, S Debiesse, C. Renault, et al.. Detection of SARS-CoV-2 antibodies using commercial assays and seroconversion patterns in hospitalized patients. Journal of Infection, In press, ⟨10.1016/j.jinf.2020.05.077⟩. ⟨hal-02862130⟩