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Updated: Aug 12, 2026
A Rapid, Multiplex Dual Reporter IgG and IgM SARS-CoV-2 Neutralization Assay for a Multiplexed Bead-Based Flow Analysis System
Published on: April 6, 2021
Virus variant-specific clinical performance of a SARS-CoV-2 rapid antigen test with focus on Omicron variants of
Linus Bornemann1, Olaf Kaup2, Johannes Kleideiter3
1Institute of Virology, University Medical Centre and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Objectives:
Antigen rapid diagnostic tests (Ag-RDTs) play an important role in the diagnosis of SARS-CoV-2. They are easier, quicker, and less expensive than the 'reference standard' RT-PCR and therefore widely in use. Reliable clinical data with respect to Ag-RDT performance in SARS-CoV-2 Omicron variants of concern (VOCs) are limited. Consequently, the objective of this study was to determine the impact different VOCs-especially Omicron-have on the clinical performance of an Ag-RDT.
Methods:
We compared the clinical performance of the Sofia SARS-CoV-2 Ag-RDT to RT-PCR in a real-world, single-centre study in a clinical point-of-care setting in patients admitted to a large hospital via the emergency department from 2 November 2020 to 4 September 2022.
Results:
Among 38 434 Ag-RDT/RT-PCR tandems taken, 1528 yielded a SARS-CoV-2 positive RT-PCR test result, with a prevalence of 4.0% (95% CI, 3.8-4.2). Overall sensitivity of the Ag-RDT was 63.7% (95% CI, 61.3-66.1) and overall specificity was 99.6% (95% CI, 99.5-99.6). Ag-RDT sensitivity was dependent on viral load (VL), because the sensitivity increased to 93.2% (95% CI, 91.5-94.6) in samples with a VL > 106 SARS-CoV-2 copies/mL. Furthermore, the Ag-RDT was more sensitive in men, and older patients. Variant-dependent sensitivity assessment showed that the sensitivity was significantly lower in Omicron-VOC (64.1%; 95% CI, 60.5-67.6) compared with SARS-CoV-2 wild-type samples (70.0%; 95% CI, 59,8-78,6) (binomial test; p value < 0.001). Analysing the limits of detection showed a 27 times higher 95% limit of detection for the Omicron-VOC BA.5 compared with the SARS-CoV-2 wild-type.
Discussion:
Ag-RDT sensitivity for detection of patients with lower VLs and with Omicron-VOC is reduced, limiting the effectiveness of Ag-RDTs. However, Ag-RDTs are still an unreplaceable tool for widely available, quick, and inexpensive point-of-care SARS-CoV-2 diagnostics.
