Evaluation of a sample pooling strategy for SARS-COV-2 by real time PCR

Abstract

Coronavirus disease 2019 (COVID-19) started as a cluster of pneumonia cases in Wuhan, China in December 2019 and became a global pandemic of international concern. Timely laboratory diagnosis of COVID-19 of all samples from both symptomatic and asymptomatic patients is key in containing the pandemic and breaking the chain of transmission. However, there is a problem of limited resources available in testing of SARS-COV-2 in low- and middle-income countries. Laboratory professionals are therefore tasked to come up with ways to overcome the burden of increasing workload and limited resources. The general objective of this study was to evaluate performance of the sample pooling strategy for SARS-COV-2 testing. Randomly selected samples were placed in pools of 5, 10 and 15 and then extracted using a Qiagen kit. Both individual RNA and pooled RNA RT-qPCR were used to screen for the E gene using a Berlin kit. In this study, among 1260 samples tested, 21 pools were positive in pools of 5 samples, 16 pools were positive in 10 sample pools and 14 were positive in pools of 15 samples, on retesting of all positive pools, 23 samples were positive. In this study, the pooling strategy saved 73 percent on the total cost of testing thus a significant reduction in resources as compared to those that were tested individually.