Evaluation of 31 Commercial SARS-CoV-2 Serology Assays

Background: The virus responsible of severe acute respiratory syndrome named SARS-CoV-2 and causing the new coronavirus disease (COVID-19) has gone global within three months. The current gold standard technique used to detect SARS-CoV-2 is real-time reverse transcription-polymerase chain reaction (rRT-PCR) from naso-pharyngeal swabs but it may be negative in up to 30% of COVID-19 patients. Detection of specific antibodies against SARS-CoV-2 may therefore enhance sensitivity of the current biological diagnosis, as well as monitor the extent of the epidemics in global or specific population, such as health-care worker. Many serological assays are currently available, but their clinical performances are still to be evaluated. Material and Method: A total of 2,594 serum samples collected from patients with SARS-CoV-2 infection documented by a positive rRT-PCR were enrolled in this study. They were tested for IgM/IgG/IgA against SARS-CoV-2 using 31 commercial assays. Antibody response was assessed depending on the onset of symptoms. In addition, 1,996 pre-epidemic serum samples expected to be negative were tested to assess specificity. Results: Rapid tests for qualitative detection of anti-SARS-CoV-2 antibodies (RDTs) achieved 77.4-100%, and ELISA/CLIA (ELISA) assays 58.8-100% for SARS-CoV-2-specific total antibodies (TAb) specificity. From 15 days after onset of symptoms, 13/18 RDT and 8/13 ELISA reached sensitivity > 90%. However, only 4 RDT and 3 ELISA assays fitted both sensitivity (> 90%) and specificity (> 98%) criteria according to French recommendations. Conclusions: Serology may offer valuable information during the course of COVID-19 pandemic, at the condition that commercial assays give reliable results. Contrasted performances were observed among the 31 commercial assays we evaluated, which underlines the importance of independent evaluation before clinical implementation. Funding Statement: This study was funded by the Agence Nationale de Recherche sur le SIDA et les Hepatites Virales (ANRS, AC43). Declaration of Interests: JM Pawlotsky has served as an advisor and/or a speaker for Abbvie, Gilead, GlaxoSmithKline, Merck, Regulus and Siemens Healthcare. C Vauloup-Fellous served as un expert (rubella and CMV serology) for Abbott Diagnostics, Roche Diagnostics, Siemens Healthcare and DiaSorin. No other authors have any competing interests to declare. Ethics Approval Statement: The study was carried out in accordance with the Declaration of Helsinki. This work was a retrospective non-interventional study with no addition to standard care procedures. Reclassification of biological remnants into research material after completion of the ordered virological tests was approved by the local interventional review board of hospital. According to the French Public Health Code (CSP Article L.1121-1.1) such protocols are exempted from individual informed consent.