Pooling Strategy for Detection of SARS-CoV-2 RNA by Real-Time RT-PCR: Comparison of Pooling 5 and 10 Samples.

Background: We evaluated whether it was appropriate to screen SARS-CoV-2 in sample pools of 5 and 10. This study was aimed to evaluate whether the pooling strategy would be an appropriate strategy for SARS-CoV-2 screening.

Methods: In the study, 5 and 10 sample pools were formed using 720 nasopharyngeal swab samples, of which 72 were positive, and 648 were negative. The samples were analyzed in three groups according to their Ct values as high, medium, and low viral load. SARS-CoV-2 RNA in nasopharyngeal swab samples was detected by the real-time PCR method on the Bio-Rad platform.

Results: The sensitivity of 5-sample pooling was 77.8%, and the sensitivity of 10-sample pooling was 75%. The false-negative rate was 22.2% in 5 sample poolings and 25% in 10 sample poolings. Out of the samples with medium and high viral loads, none of the positive samples were lost in either pool. In pools containing both 5 samples and 10 samples, the individual mean Ct values of the samples detected as false-negative were significantly higher (low viral load) than those of the other samples (p < 0.001).

Conclusions: In this study, 5 and 10 pooling seems useful in detecting patients with medium and high viral loads. Pooling strategies that allow mass screening of SARS-CoV-2 can contribute to early detection of patients at high risk of SARS-CoV-2 transmission in low prevalence areas, as well as timely public health interventions.