Preliminary evaluation of Roche Cobas Elecsys Anti-SARS-CoV-2 chemiluminescence immunoassay

The results of this preliminary investigation on Elecsys Anti-SARS-CoV-2, based on its comparison with the Euroimmun Anti-SARS-CoV-2 IgG and IgA immunoassays, paves the way to some conclusions. First, a good correlation was found between the raw values of the new Roche total antibodies immunoassay and those of both Euroimmun IgGs and IgAs. Then, a good agreement was also found between the total antibodies measure and that of IgGs and IgAs combined or alone, with AUCs always >0.83 and agreement >94%. Therefore, although we could not evaluate IgM immune response in this study, it can be inferred that minor differences have emerged from using Elecsys Anti-SARS-CoV-2 total antibodies or Euroimmun Anti-SARS-CoV-2 IgGs and IgAs in our population screening, thus complementing previous evidence published by Egger et al using another anti-SARS-CoV-2 IgM and IgG ELISA. It is also noteworthy that an especially high concordance was noted when comparing data obtained with Euroimmun IgG antibodies positivity and Elecsys Anti-SARS-CoV-2 total antibodies. In particular, four more samples were found to be positive Elecsys Anti-SARS-CoV-2 than with Euroimmun IgG, which may reflect perhaps the presence of IgM, which could not be evaluated in this study. A further investigation of these cases showed that one had undermined results of nucleic acid amplification test (NAAT) on nasopharyngeal swabs, one was found to be negative and the remaining two were instead positive. This would actually suggest that Elecsys Anti-SARS-CoV-2 total antibodies may perhaps be characterized by higher diagnostic sensitivity in detecting acute SARS-CoV-2 infection, though further studies will be needed to verify this assumption.