Large-scale implementation of pooled RNA extraction and RT-PCR for SARS-CoV-2 detection

Ben-Ami, Roni; Klochendler, Agnes; Seidel, Matan; Sido, Tal; Gurel-Gurevich, Ori; Yassour, Moran; Meshorer, Eran; Benedek, Gil; Fogel, Irit; Oiknine-Djian, Esther; Gertler, Asaf; Rotstein, Zeev; Lavi, Bruno; Dor, Yuval; Wolf, Dana G.; Salton, Maayan; Drier, Yotam

OBJECTIVES: Testing for active SARS-CoV-2 infection is a fundamental tool in the public health measures taken to control the COVID-19 pandemic. Due to the overwhelming use of SARS-CoV-2 RT-PCR tests worldwide, availability of test kits has become a major bottleneck, while the need to increase testing throughput only rises. We aim to overcome these challenges by pooling samples together, performing RNA extraction and RT-PCR in pools. METHODS: We tested the efficiency and sensitivity of pooling strategies for RNA extraction and RT-PCR detection of SARS-CoV-2. We tested 184 samples both individually and in pools to estimate the effects of pooling. We further implemented Dorfman pooling with a pool size of 8 samples in large-scale clinical tests. RESULTS: We demonstrated pooling strategies that increase testing throughput while maintaining high sensitivity. A comparison of 184 samples tested individually and in pools of 8 samples, showed that test results were not significantly affected. Implementing the 8-sample Dorfman pooling to test 26,576 samples from asymptomatic individuals, we identified 31 (0.12%) SARS-CoV-2 positive samples, achieving a 7.3-fold increase in throughput. CONCLUSIONS: Pooling approaches for SARS-CoV-2 testing allow a drastic increase in throughput while maintaining clinical sensitivity. We report the successful large-scale pooled screening of asymptomatic populations.