EVALUATION OF THE ABBOTT SARS-COV-2 IG-G ASSAY.

Lau, C.; Hoo, S.; Liang, Y.; Aw, T.

Introduction: Antibodies to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can increase as soon as 10-13 days after infection. We describe our evaluation of the Abbott SARS-CoV-2 IgG assay on the Architect immunoassay analyser. Methods: We assessed the precision, sensitivity, and specificity of the Abbott SARS-CoV-2 IgG assay in samples from polymerase chain reaction (PCR) positive patients and healthy healthcare workers. The manufacturer cut-off index (COI) of 1.4 was adopted to identify positive results. We examined the assay cross-reactivity with other viral antibodies (influenza/dengue/hepatitis C/hepatitis B) and rheumatoid factor (RF). The sample throughput of the Abbott assay was also assessed. Results: The Abbott assay showed excellent precision, with a CV of 3.4% for the negative control (COI = 0.06) and 1.6% for a high positive serum sample (COI = 8.6). Residual serum was available from 57 inpatients not initially suspected of having COVID-19, 29 of whom tested positive for SARS-CoV-2 IgG. The Abbott assay has a sensitivity of 90.9-100% when tested in 54 subjects [≥]14 days post PCR positive, and a specificity of 100% (N = 358). There was no cross-reactivity with other viral antibodies (influenza/dengue/hepatitis C/hepatitis B) and RF. The Architect Abbott assay has a throughput of 100 samples in 70 minutes. Conclusion: The Abbott SARS-CoV-2 IgG assay shows excellent performance that is well within FDA and CDC guidelines when testing patients [≥]14 days POS with little cross-reactivity from other viral antibodies. There is some evidence that SARS-CoV-2 IgG develops early in the disease process.