Two-Stage Hierarchical Group Testing Strategy to Increase SARS-CoV-2 Testing Capacity at an Institution of Higher Education: A Retrospective Analysis.

Population testing for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is necessary owing to the potential for viral transmission from asymptomatic cases, yet scarcity of reagents and equipment has increased the cost-prohibitive implementation of screening campaigns at institutions of higher education. Significant analytical sensitivities of nucleic acid amplification methods permit sample pooling to increase testing capacity. Statistical models compared optimal testing configuration for pools of 3, 5, and 10 samples. Assessment of pooling using the TaqPath COVID-19 Combo Kit multiplex assay (ORF1ab, N, and S gene targets) involved a limit of detection (LOD) study, matrix effect study, and clinical comparison of neat to pooled sample. An LOD of 135.02 (ORF1ab; CI.95: 117.21-155.52), 373.92 (N; CI.95: 257.05-437.64), and 1001.32 (S; CI.95: 896.62-1118.33) gce per milliliter was resolved. Seventy-two randomly selected samples demonstrated slight suppression due to negative sample matrix. Resulting mean cycle threshold (CT) shifts were 2.09 (ORF1ab), 1.76 (N), and 2.31 (S) for the 3-pool, 2.83 (ORF1ab), 2.45 (N), and 3.24 (S) for the 5-pool, and 3.99 (ORF1ab), 3.46 (N), and 4.07 (S) for the 10-pool. Despite quantitative sensitivity loss trend, the qualitative result was unaffected in each pool. According to the range of disease prevalence observed at the testing site (0.03-7.32%), a pool of five samples was deemed an optimal and cost-effective option for monitoring the Northeastern University community.