Analytical Accuracy of VIDAS Severe Acute Respiratory Syndrome Coronavirus 2 Based on Enzyme-linked Fluorescent Assay for the Detection of Immunoglobulin M and Immunoglobulin G Antibodies in Coronavirus Disease 2019 Infection

Abstract Introduction: A new emergent coronavirus disease 2019 (COVID-19) is a pandemic infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Serological tests have got a lot of attention as an alternative to reverse transcription polymerase chain reaction (RT-PCR) in the diagnosis of acute and chronic infection. Several anti-SARS-CoV-2 antibodies (immunoglobulin [Ig] M and IgG) detection immunoassays methods are available with variable sensitivity and specificity. The present study conducted to determine the diagnostic accuracy of enzyme-linked fluorescence assay on VIDAS for the detection of IgM and IgG Antibodies against SARS-CoV-2 infection. Materials and Methods: One thousand and eighteen serum samples taken from the COVID-19 and non-COVID-19 groups confirmed by RT-PCR were analyzed to determine the diagnostic accuracy of SARS-CoV-2 IgM and IgG by an enzyme-linked fluorescence assay on VIDAS. Blood samples from research participants were collected on an average 18 days (from 8 to 20 days) after the onset of symptoms. Results: Most of them in the non-COVID-19 group (47.4%) and COVID-19 group (52.5%) were in the age group of 26–50 years. Although the manufacturer’s cut-off of 1.0 AU/mL for SARS-CoV-2 IgM antibodies had 100.0% specificity to detect the infected and at the cut-off of 0.1 AU/mL obtained by Youden’s index had highest sensitivity (0.1 AU/mL – 99.6% vs. 1.0 AU/mL – 54.9%) and specificity 100%. Similarly for SARS-CoV-2 IgG antibodies, both the manufacturer’s cut-off of 1.0 AU/mL and 0.5 AU/mL have almost comparable performances with slightly better sensitivity (1 AU/mL – 92.4%; 0.5 AU/mL – 94.3%) to detect the infected and specificity of 100%. Conclusion: The diagnostic efficiency of enzyme-linked fluorescence assay showed overall high sensitivity and specificity on VIDAS for SARS-CoV-2-specific antibodies IgM and IgG. IgM and IgG cutoff values of 0.1 AU/mL and 0.5 AU/mL, respectively, performed much better than the manufacturer’s cut off for the diagnosis of COVID-19.