Clinical diagnostic performance evaluation of five immunoassays for antibodies to SARS-CoV-2 diagnosis in a real-life routine care setting

Abstract

While molecular techniques remain the gold standard for diagnosis of acute SARS-CoV-2 infection, serological tests have the unique potential to ascertain how much of the population has been exposed to the COVID-19 pathogen. There have been limited published studies to date documenting the performance of SARS-CoV-2 antibody assays in Nigeria and so we evaluated the diagnostic performance of five (5) immunoassay on a set of clinical samples. Five automated immunoassays (2019-nCoV IgG/IgM antibody determination kit, Tigsun COVID-19 combo IgM/IgG rapid test, rapid response COVID-19 IgG/IgM test, COVID-19 IgM-IgG combined antibody rapid test, iChroma COVID-19 Ab) were tested. Three hundred and fourteen specimens were analyzed from health care workers who tested positive PCR for SARS-CoV-2 with symptoms consistent with SARS-CoV-2 receiving treatment at two treatment centres in Nasarawa State from March to September, 2020 with control of 134 health care workers who tested negative PCR for SARS-CoV-2 with no symptoms to SARS-CoV-2. The median patients' age was 40 years (IQR 39.8-41), majority were male and were on admission. The SARS-CoV-2 IgG/IgM antibody evaluated kits had a sensitivity of 33% (2019-nCoV IgG/IgM antibody determination kit), 22% (Tigsun COVID-19 combo IgM/IgG rapid test), 43% (rapid response COVID-19 IgG/IgM test), 44% (COVID-19 IgM-IgG combined antibody rapid test), 25% (iChroma COVID-19 Ab), 100% sensitivity, accuracy of 68.5% and Kappa coefficient of 0.7 and rapid response COVID-19 IgG/IgM test cassette had a sensitivity of 33%, specificity of 100% and accuracy of 72.5% with Kappa coefficient 0.7. The Tigsun COVID-19 combo IgM/IgG rapid test (lateral flow), positive, COVID-19 IgM-IgG combined antibody rapid test and iChroma COVID-19 Ab RT all had sensitivity of zero percent. Serology was complementary to RT-PCR for the diagnosis of COVID-19 at least 14 days after onset of symptoms. The assay panel needs to be improved to serve as an option for the diagnosis of SARS-CoV-2 in resource constrained settings where there are limited molecular diagnostics testing panels.