Performance of the EUROIMMUN Anti-SARS-CoV-2 ELISA Assay for detection of IgA and IgG antibodies in South Africa

Abstract

Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) has been identified as the causative agent for causing the clinical syndrome of COVID -19. Accurate detection of SARS-CoV-2 infection is not only important for management of infected individuals but also to break the chain of transmission. South Africa is the current epicenter of SARS-CoV-2 infection in Africa. To optimize the diagnostic algorithm for SARS-CoV-2 in the South African setting, the study aims to evaluate the diagnostic performance of the EUROIMMUN Anti-SARS-CoV-2 assays. This study reported the performance of EUROIMMUN enzyme-linked immunosorbent assay (ELISA) for semi-quantitative detection of IgA and IgG antibodies in serum and plasma samples targeting the recombinant S1 domain of the SARS-CoV-2 spike protein as antigen. Samples were collected from 391 individuals who had tested positive for SARS-CoV-2 and 139 SARS CoV-2 negative controls. Samples were stratified by number of days’ post-PCR diagnosis and symptoms. The sensitivity of EUROIMMUN IgG was 64.1% (95% CI: 59.1–69.0%) and 74.3% (95% CI: 69.6–78.6%) for IgA and the specificity was lower for IgA [84.2% (95% CI: 77–89.2%)] than IgG [95.2% (95% CI: 90.8–98.4%)]. The EUROIMMUN Anti-SARS-CoV-2 ELISA Assay sensitivity was higher for IgA but low for IgG and improved for both assays in symptomatic individuals and at later timepoints post PCR diagnosis.

Comparison of antibody immune responses between BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines in naïve and previously infected individuals

“…EI 2606-9601 A, Germany) was used to measure the anti-S1 IgA antibody levels. 13 The IgA ratio was calculated by dividing the extinction of the sample by the calibrator. Ratios ≥1.1 were considered positive, > 0.8 negative and ≥0.8 to > 1 borderline.…”

High but Short-lived anti-SARS-CoV2 neutralizing, IgM, IgA, and IgG levels among mRNA-vaccinees compared to naturally-infected participants

“…The IgA ratio was calculated by dividing the extinction of the sample by the calibrator. Ratios < 8 were considered negative, and ≥ 0.8 were considered positive (18). IgM levels were measured using the automated analyzer Vidas® 3 from BioMeriux Diagnostics (Cat.…”

Anti SARS-CoV2 seroprevalence in Zanzibar in 2021 before the Omicron wave

“…The EUROIMMUN Anti-SARS-CoV-2 ELISA (IgG) kit provided a semi-quantitative analysis detecting human IgG antibodies against S1 domain of SARS-CoV-2 spike protein indicating prior infections and has been recommended for seroprevalence surveys like this (Gededzha et al ., 2021). Using the calibrator of the kit, a ratio-based analysis (OD of sample/OD of calibrator) of the obtained data was performed to differentiate between negative (ratio below 0.8), positive (ratio above 1.1) and borderline cases.…”