Comparison of Five Serological Assays for the Detection of SARS-CoV-2 Antibodies

Serological assays can contribute to the estimation of population proportions with previous immunologically relevant contact with the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) virus. In this study, we compared five commercially available diagnostic assays for the diagnostic identification of SARS-CoV-2-specific antibodies. Depending on the assessed immunoglobulin subclass, recorded sensitivity ranged from 17.0% to 81.9% with best results for immunoglobulin G. Specificity with blood donor sera ranged from 90.2% to 100%, with sera from EBV patients it ranged from 84.3% to 100%. Agreement from fair to nearly perfect was recorded depending on the immunoglobulin class between the assays, the with best results being found for immunoglobulin G. Only for this immunoglobulin class was the association between later sample acquisition times (about three weeks after first positive PCR results) and positive serological results in COVID-19 patients confirmed. In conclusion, acceptable and comparable reliability for the assessed immunoglobulin G-specific assays could be shown, while there is still room for improvement regarding the reliability of the assays targeting the other immunoglobulin classes.