Verification and Comparison of Qualitative Serological Assays for Anti-SARS-COV-2 IgM and IgG Antibodies Detection.

Background: Due to their wide application in the SARS-CoV-2 pandemic, we verified and compared three qualitative serological methods in order to select the most optimal that will best serve its purpose under laboratory conditions.

Methods: We assessed the diagnostic characteristics of two automated serological methods (Roche Elecsys^® Anti-SARS-CoV-2 and Abbott SARS-CoV-2 IgG) and a POCT test (Colloidal Gold Method SARS-CoV-2 IgM/IgG Antibody Assay Kit). In the process of verification, analytical precision was also assessed for the automated assays.

Results: Diagnostic characteristics were determined by measuring antibodies against SARS-CoV-2 in 91 RT-PCR-negative and 60 RT-PCR-positive samples. The POCT test gave the highest number of false positive cases (8.61%). Roche Elecsys^® Anti-SARS-CoV-2 gave only 2.65% false positivity and showed the highest diagnostic sensitivity of 98.33% (95% CI: 91.06-99.96), while Abbott SARS-CoV-2 IgG method showed 100.00% (95% CI: 96.03-100.00) diagnostic specificity and an almost perfect agreement with Roche Elecsys^® Anti-SARS-CoV-2. When assessing the precision of the automated methods, we observed some variability in the positive control samples, but the values did not affect clinical interpretation.

Conclusion: Both automated methods demonstrate superior diagnostic characteristics compared to the Colloidal Gold Method, and this POCT test is not considered as an appropriate choice for routine testing. The two automated methods showed low variability without altering the results and their interpretation.