Evaluation Of The Abbott SARS-COV-2 Ig-G Assay.

IntroductionAntibodies 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. MethodsWe 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. ResultsThe 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. ConclusionThe 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. IMPACT STATEMENTWith the current SARS-CoV-2 pandemic still ongoing, laboratories are hard pressed to introduce SARS-CoV-2 antibody testing to help as an indirect marker for infection to identify patients with prior infection/exposure. The Abbott SARS-CoV-2 IgG assay has excellent performance with good precision, specificity, and sensitivity [≥]14 days after a positive SARS-CoV-2 PCR test, with a competitive throughput of 100 samples in 70 minutes. It shows no cross-reactivity with other viral antibodies (influenza/dengue/hepatitis B/hepatitis C) and rheumatoid factor. We have also found evidence of early antibody development in some patients before they tested positive on the SARS-CoV-2 PCR test.