Rapid comparative evaluation of SARS-CoV-2 rapid point-of-care antigen tests (preprint)

ABSTRACT

Background Currently, more than 500 different AgPOCTs for SARS-CoV-2 diagnostics are on sale (July 2021), for many of which no data about sensitivity other than self-acclaimed values by the manufacturers are available. In many cases these do not reflect real-life diagnostic sensitivities. Therefore, manufacturer-independent quality checks of available AgPOCTs are needed, given the potential implications of false-negative results. Objective The objective of this study was to develop a scalable approach for direct comparison of the analytical sensitivities of commercially available SARS-CoV-2 antigen point-of-care tests (AgPOCTs) in order to rapidly identify poor performing products. Methods We present a methodology for quick assessment of the sensitivity of SARS-CoV-2 lateral flow test stripes suitable for quality evaluation of many different products. We established reference samples with high, medium and low SARS-CoV-2 viral loads along with a SARS-CoV-2 negative control sample. Test samples were used to semi-quantitatively assess the analytical sensitivities of 32 different commercial AgPOCTs in a head-to-head comparison. Results Among 32 SARS-CoV-2 AgPOCTs tested, we observe sensitivity differences across a broad range of viral loads (∼7.0 * 10 8 to ∼1.7 * 10 5 SARS-CoV-2 genome copies per ml). 23 AgPOCTs detected the Ct25 test sample (∼1.4 * 10 6 copies/ ml), while only five tests detected the Ct28 test sample (∼1.7 * 10 5 copies/ ml). In the low range of analytical sensitivity we found three saliva spit tests only delivering positive results for the Ct21 sample (∼2.2 * 10 7 copies/ ml). Comparison with published data support our AgPOCT ranking. Importantly, we identified an AgPOCT offered in many local drugstores and supermarkets, which did not reliably recognize the sample with highest viral load (Ct16 test sample with ∼7.0 * 10 8 copies/ ml) leading to serious doubts in its usefulness in SARS-CoV-2 diagnostics. Conclusion The rapid sensitivity assessment procedure presented here provides useful estimations on the analytical sensitivities of 32 AgPOCTs and identified a widely-spread AgPOCT with concerningly low sensitivity.