Limit of detection in different matrices of nineteen commercially available rapid antigen tests for the detection of SARS-CoV-2

Abstract

In the context of the coronavirus disease 2019 (COVID-19) pandemic there has been an increase of the use of antigen-detection rapid diagnostic tests (Ag-RDT). The performance of Ag-RDT vary greatly between manufacturers and evaluating their analytical limit of detection (LOD) has become high priority. Here we describe a manufacturer-independent evaluation of the LOD of 19 marketed Ag-RDT using live SARS-CoV-2 spiked in different matrices: direct culture supernatant, a dry swab, and a swab in Amies. Additionally, the LOD using dry swab was investigated after 7 days’ storage at -80°C of the SARS-CoV-2 serial dilutions. An LOD of ≈ 5.0 x 102 pfu/ml (1.0 x 106 genome copies/ml) in culture media is defined as acceptable by the World Health Organization. Fourteen of nineteen Ag-RDTs (ActiveXpress, Espline, Excalibur, Innova, Joysbio, Mologic, NowCheck, Orient, PanBio, RespiStrip, Roche, Standard-F, Standard-Q and Sure-Status) exceeded this performance criteria using direct culture supernatant applied to the Ag-RDT. Six Ag-RDT were not compatible with Amies media and a decreased sensitivity of 2 to 20-fold was observed for eleven tests on the stored dilutions at -80°C for 7 days. Here, we provide analytical sensitivity data to guide appropriate test and sample type selection for use and for future Ag-RDT evaluations. 201/200

The Impact of Universal Transport Media and Viral Transport Media Liquid Samples on a SARS-CoV-2 Rapid Antigen Test

“…[2][3][4][5] It is important for rapid antigen manufacturers to understand how UTM/VTM samples may affect assay performance. 6 The major issues with these samples are swab sample dilution (e.g., decreased analyte concentration), swab sample dilution on extraction buffer components (surfactant, pH, and ionic strength), and UTM/VTM formulations (e.g., fetal calf serum, bovine serum albumin, gelatin, amino acids, metabolites, and dyes). To understand how UTM/VTM samples affect the performance of the Healgen rapid antigen test, we performed three different studies: 1) a dilution study using several different UTM/VTMs, 2) a study to determine the impact of UTM/VTM liquid sample dilution on the surfactant concentration of the viral extraction solution, pH, and ionic strength, and 3) a study to investigate concentrations of UTM/VTM components.…”