High capacity clinical SARS-CoV-2 molecular testing using combinatorial pooling

Abstract The SARS-CoV-2 pandemic led to unprecedented testing demands, causing significant testing delays globally. One strategy used for increasing testing capacity was pooled-testing, using a two-stage technique first introduced during WWII. Here we report the development, validation and clinical application of P-BEST - a single-stage pooled-testing strategy that was approved for clinical use in Israel. P-BEST was clinically evaluated using 3,636 side-by-side tests and was able to correctly detect all positive samples and accurately estimate their Ct value. P-BEST was then used to clinically test 837,138 samples using 270,095 PCR tests - a 3.1 fold reduction in the number of tests. Importantly, P-BEST was also used during the Alpha and Delta waves, when positivity rates exceeded 10%, rendering traditional pooling non-practical. We also describe a tablet-based solution that allows performing manual single-stage pooling in settings where liquid dispensing robots are not available. Our data provides a proof-of-concept for large-scale clinical implementation of single-stage pooled-testing for continuous surveillance of multiple pathogens with reduced test costs, and as an important tool for increasing testing efficiency during pandemic outbreaks.