Evaluation of Analytical Performance of Seven Rapid Antigen Detection Kits for Detection of SARS-CoV-2 Virus

Abstract

Background: Early diagnosis of the novel coronavirus disease of 2019 (COVID-19) in asymptomatic and symptomatic patients is crucial to identify infectious individuals and to help prevent the spread of the virus in the community. Several assays have been developed and are in use in today's clinical practice. These assays vary in their analytical and clinical performance. For an accurate diagnosis, medical professionals must become more familiar with the test's utility to select the most appropriate test. This study aims to evaluate the analytical performance of rapid antigen tests used for the detection of SARS-CoV-2 viral antigen compared to RT-PCR SARS-CoV-2 molecular assay. Methods: Oropharyngeal swab specimens from five COVID-19 patients were tested by seven rapid antigen tests developed by different IVD companies. RT-PCR to detect specific RNA fragments of SARS-CoV-2 was used as a confirmatory test. The cycle threshold (Ct) value, which often reflects viral load, in these specimens ranged from 15 to 35. For the analytical evaluation, extraction fluid of each antigen kit was spiked with attenuated ATCC virus at different concentrations ranging from 4.6x10 4 /mL to 7.5x10 5 /mL and tested with antigen testing kits. Results: Out of five confirmed positive SARS-CoV-2 specimens by RT-PCR, only one sample showed a positive result by one of the seven evaluated antigen testing kits. The positive result was observed in the specimen with a Ct value of 15. All other evaluated rapid tests were negative for all five positive specimens. This was further confirmed with the spiking study using ATCC attenuated virus, where extraction fluid of each rapid test was spiked with concentrations ranging from 4.6x10 4 /mL to 7.5x10 5 /mL. None of these spiked specimens showed positive results, indicating very low sensitivity of these antigen kits. Conclusion: This comparison study shows that rapid antigen tests are less sensitive than RT-PCR tests and are not reliable tests for testing asymptomatic patients, who often carry low viral load. Analytical performance of rapid antigen tests should be thoroughly evaluated before implementing it at clinical decision level.

COVID-19 Endothelial Dysfunction Can Cause Erectile Dysfunction: Histopathological, Immunohistochemical, and Ultrastructural Study of the Human Penis

“…We could not detect viral protein in penis tissue by immunohistology, possibly due to comparably low viral RNA load in the penis. This result was not surprising since recent studies show that COVID-19 isolation is unlikely from samples with low RNA loads [ 4 ]. H&E staining from our specimens did not show significant results compared to previous studies in which COVID-19 infection caused mild to moderate accumulation of lymphomonocytic inflammatory cells in a perivascular or subendothelial distribution [ 5 ].…”

Development and Clinical Evaluation of an Immunochromatography-Based Rapid Antigen Test (GenBody™ COVAG025) for COVID-19 Diagnosis

“…Ag-RDT has been reported to have high specificity, but its use in clinical diagnosis is sometimes questioned because of its low sensitivity. Recent studies showed Ag-RDT is unable to detect SARS-CoV-2 at a Ct value of more than 19 [ 22 ]. Other reports have revealed the diagnostic sensitivity of Ag-RDT to be 95% at Ct values < 25 but declines drastically to 20–40% when the Ct value is > 25 [ 23 ].…”

Diagnostic Utility of Antigen Detection Rapid Diagnostic Tests for Covid- 19: a Systematic Review and Meta-analysis

“…The possible interference of time of testing cannot be ruled out. Some researchers revealed that testing less than 5 days from the onset of symptoms increases sensitivity (9,10,23,31). It is inconsistent with previous reports that a load of infectious virus decreases after 7-10 days (10,45).…”

“…Summary ROC curves constructed for all assays based on Monte Carlo simulations are shown in Fig.2. It did not apply to assessing the false results, because 7 studies (35%) did not focus on false results (8,10,23, 28,31,33, 38,39). Some of the current kinds of literature which focused on Ab rapid tests were excluded due to reporting the results as the separate sensitivity for IgG and IgM or analyzed data based on onset of symptoms(4,40).…”