Table 2. Preliminary testing of sample pooling method on retrospective samples for the detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by qRT-PCR.
| Pool ID | Pooled samples (10 specimens/pool)b | Results of qRT-PCRa (CT value) | |
|---|---|---|---|
| Individual testing | Pooled testingc | ||
| A | 1 positive (IMU0255) + 9 negatives | CT = 36.24 (1.35) | CT = 37.54 (0.40) |
| B | 10 negatives | Not Detected | Not Detected |
| C | 10 negatives | Not Detected | Not Detected |
| D | 10 negatives | Not Detected | Not Detected |
| E | 1 positive (IMU0094) + 9 negatives | CT = 17.59 (0.90) | CT = 22.36 (0.22) |
| F | 10 negatives | Not Detected | Not Detected |
| G | 2 positives (IMU0254 & IMU0256) + 8 negatives | CT = 31.24 (0.36) | CT = 36.40 (1.04) |
| CT = 37.49 (0.49) | |||
| H* | 10 negatives | Not Detected | CT = 39.46 (0.57) |
| I* | 10 negatives | Not Detected | CT = 40.38 (0.60) |
| J | 1 positive (IMU0448) + 9 negatives | CT = 30.02 (0.33) | CT = 31.39 (0.29) |
| AA | 10 negatives | Not Detected | Not Detected |
| BB | 10 negatives | Not Detected | Not Detected |
| CD | 10 negatives | Not Detected | Not Detected |
| DD | 10 negatives | Not Detected | Not Detected |
| EE | 1 positive (IMU0139) + 9 negatives | CT = 37.06 (0.32) | CT = 37.70 (0.17) |
a The qRT-PCR was performed in triplicates; The CT values are expressed as mean (standard deviation); A pool or sample was considered positive for COVID-19 if the CT value was less than or equal to 38.
b All clinical NP/OP swab specimens used were previously tested for SARS-CoV-2 (n = 150); Six clinical specimens with a range of CT values that previously tested positive for SARS-CoV-2 by qRT-PCR assay were used to spike the pools.
c The volume of clinical specimen used for pooled testing (10-sample pool) is 60 μL.
* CT values of 39.46 and 40.38 were detected for Groups H and I, respectively. These results were regarded as negative for COVID-19 in this case.