Assessment of twenty-two SARS-CoV-2 rapid antigen tests against SARS-CoV-2: A laboratory evaluation study

Abstract

BackgroundRapid antigen testing is widely used as a way of scaling up population-level testing. To better inform antigen test deployment in Australia, we evaluated 22 commercially available antigen tests against the currently circulating delta variant, including an assessment of culture infectivity.MethodsAnalytical sensitivity was evaluated against SARS-CoV-2 B.1.617.2 (Delta), reported as TCID50/mL, cycle threshold (Ct) and viral load (RNA copies/mL). Specificity was assessed against non-SARS-CoV-2 viruses. Clinical sensitivity and correlation with cell culture infectivity was assessed using the Abbott PanBio™ COVID-19 Ag test.ResultsNineteen kits consistently detected SARS-CoV-2 antigen equivalent to 1.3 × 106 copies/mL (5.8 × 103 TCID50 /mL). Specificity for all kits was 100%. Compared to RT-PCR the Abbott PanBio™ COVID-19 Ag test was 52.6% (95% CI, 41.6% to 63.3%) concordant, with a 50% detection probability for infectious cell culture at 5.9 log10 RNA copies/mL (95% CI, 5.3 to 6.5 log10 copies/mL). Antigen test concordance was 97.6% (95% CI, 86.3% to 100.0%) compared to cell culture positivity.ConclusionsAntigen test positivity correlated with positive viral culture, suggesting antigen test results may determine SARS-CoV-2 transmission risk. Analytical sensitivity varied considerably between kits highlighting the need for ongoing systematic post-market evaluation to inform test selection and deployment.

Evaluation of Four Strategies for SARS-CoV-2 Detection: Characteristics and Prospects

“…With the advantages of being free of laboratory settings, offering a shorter time to result, and being mass and cost-effective to manufacture, they can act as a potential alternative method if molecular tests are not available ( 36 ). Our study revealed that the detection performance of different rapid antigen kits varied greatly, and the lowest concentrations that achieved a 100% rate of detection success ranged from 10 4 to 10 6 copies/mL for inactivated cell culture supernatants and from 1 to 150 ng/mL for recombinant N proteins, which was essentially consistent with the findings reported in previously published articles ( 35 , 37 ). The antibody labeling method of rapid antigen tests would affect their analytical performance, and the fluorescence microsphere was observed to enhance the sensitivity of the analytical signal by 10 to 100-fold compared to that of the latex microsphere and colloidal gold ( 38 ).…”

“…Unexpectedly, the Ustar nucleic acid POCT, which combines cross-priming amplification (CPA) and nucleic acid lateral flow technologies, can detect samples at concentrations as low as 1.42 × 10 3 copies/mL, showing excellent performance in the detection of SARS-CoV-2 in the study. With a short turnaround time, portable procedures ( 33 ), and an analytical sensitivity comparable to that of the gold standard rRT-PCR, nucleic acid POCT is a promising diagnostic agent for aiding in the expansion of testing ( 34 ) and can be used as confirmatory testing where laboratory-based nucleic acid amplification testing is not available ( 35 ). However, due to the scarcity of portable nucleic acid POCT assays validated in China, only one CE-IVD marked kit was included in the study.…”

Analytical Sensitivity of Lateral Flow Devices against SARS-CoV-2 Omicron Subvariants BA.4, BA.5, and BA.2.75

“…Isolates were grown as previously described ( 3 ) and harvested when cytopathic effect (CPE) was observed. For each variant, we constructed a 10-fold dilution range of quantified virus spanning ~2 × 10 8 to 2 × 10 5 copies/mL, corresponding to N gene cycle threshold (Ct) values of ~19 to ~29 on an in-house real-time RT-PCR assay ( 5 ), and using droplet digital PCR (ddPCR) ( 3 ). Testing was performed in quadruplicate using live virus at Biosafety Level 3, and limit of detection (LOD) was defined as the last dilution where all four replicates were positive.…”

Diagnostic Approaches For COVID-19: Lessons Learned and the Path Forward

“…In the one-step testing method, the patient's sample is collected and tested on site at the patient's point-of-care side. high with minimal value of 1 cP/reaction 22,23 good and varies based on the test with a minimum of 900 copies/mL 24, 25 good with a minimum of 1 × 10 6 copies/mL 26,27 good but cannot be used to diagnose active infection 25 sensitivity: high good low, especially for the samples with Ct > 35…”