Do fully automated immunoassays for the evaluation of the immune response to SARS-CoV-2 are commutable?

On December 30, 2019, the city of Wuhan, China, experienced an outbreak of unexplained pneumonia. From January 7, 2020, a new betacoronavirus, severe acute respiratory syndrome coronavirus was identified (SARS-CoV-2). The World Health Organization (WHO) has since declared a pandemic with millions of confirmed cases worldwide. As part of the fight against the epidemic, laboratories have a critical role in assessing the reliability of new serological assays before taking part of diagnostic protocols or made available broader to the community and to evaluate commutability between assays. The aim of this study was to perform a comparison between two automated assays for SARS-CoV-2 IgG testing, the MAGLUMI ® 800 and the LIAISON ® XL. Among the patients confirmed positive for COVID-19, the two automated assays were significantly correlated (r = 0.811; p < 0.0001). The overall concordance made for MAGLUMI 2019-nCoV IgG positive/negative vs. LIAISON® SARS-CoV-2 IgG positive/negative results was 79 % (Index Kappa of Cohen). We list the discrepancies between the two analyzers among the 44 tested patients. In conclusion, the overall agreement between the two automated assays for SARS-CoV-2 was good. However, the MAGLUMI assay might be more sensitive at the early stages of antibody development and there is a lack of specificity with LIAISON XL.