Comparative assessment of SARS-CoV-2 serology in healthcare workers with Abbott Architect, Roche Elecsys and The Binding site ELISA immunoassays
Authors: Mohanraj Dinesh , Whitelegg Alison , Bicknell Kelly , Bhole Malini , Taylor Lorna , Webber Caroline 
Published: March 2021

AbstractPurposeSARS-CoV-2 serology testing is key for assessing seroprevalence and antibody response post-vaccination in immunocompromised patients. Evaluation of current SARS-CoV-2 serological assays have been performed on samples from severe COVID-19 hospitalised patients. However, robust assay development requires assessment in asymptomatic and non-hospitalised individuals to determine if serological assays are sensitive to detect waning and mild antibody responses. Our study evaluated the performance characteristics between two high-throughput SARS-CoV-2 IgG nucleocapsid assays (Abbott and Roche) and The binding site (TBS) Anti-Spike IgG/A/M ELISA kit in healthcare workers.Methods236 samples were collected from Portsmouth Hospital University NHS Trust (PHU) and The Dudley Group NHS Trust and analysed for SARS-CoV-2 serology. We derived concordance, agreement and assay performance as well as using receiver operating characteristic (ROC) curves to redefine the assay threshold of the Abbott assay.ResultsResult concordance between the Abbott and TBS was 66%. Discrepant samples were analysed using the Roche assay which showed 100% agreement with the TBS assay. In samples analysed >58 days post-PCR, the sensitivity of Abbott and Roche was 100%. In samples analysed >100 days post-PCR the sensitivity of the Abbott assay dropped to 77.2% but remained at 100% for the Roche assay. A redefined Abbott threshold of 0.64 increased the sensitivity to 90% giving results similar to Roche and TBS assaysConclusionThis study demonstrated Abbott assay had a lower sensitivity in comparison to TBS and Roche. Furthermore, TBS can be implemented as a viable alternative for SARS-CoV-2 serology testing where high-throughput assays are not available on site.Trial registration number and date of registrationNot applicable.Trial registration number, date of registration followed by “retrospectively registered”Not applicable.AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology testing is key for assessing seroprevalence and antibody response post-vaccination in immunocompromised patients. Here we performed a comparison between two high-throughput nucleocapsid assays (Abbott SARS-CoV-2 IgG and Roche Elecsys Anti-SARS-CoV-2) and The Binding Site (TBS) anti-Spike IgG/A/M-SARS-CoV-2 ELISA kit. 236 samples were collected across 2 sites, Portsmouth Hospital University NHS Trust (PHU) and The Dudley Group NHS Trust. We derived concordance, agreement and assay performance as well as using receiver operating characteristic (ROC) curves to redefine the assay threshold of the Abbott assay. Result concordance between the Abbott and TBS was 66%. Discrepant samples were analysed using the Roche assay which showed 100% agreement with the TBS assay. In samples analysed >58 days post-PCR, the sensitivity of Abbott and Roche was 100%. In samples analysed >100 days post-PCR the sensitivity of the Abbott assay dropped to 77.2% but remained at 100% for the Roche assay. A redefined Abbott threshold of 0.64 increased the sensitivity to 90% giving results similar to the Roche and TBS assays. In conclusion, this study demonstrated Abbott assay had a lower sensitivity in comparison to TBS and Roche. This study established TBS can be implemented as a viable alternative for SARS-CoV-2 serology testing where high-throughput assays are not available on site. Furthermore, anti-spike assays, such as TBS, could be used to monitor vaccination responses to deduce SARS-CoV-2 population-immunity. Further optimisation studies are required to evaluate the performance characteristics of these assays which could facilitate widescale sero-epidemiological surveillance.