Table 2.
EDx dilution series tested using the SARS-CoV-2 RT-PCR E gene reference*, E-GUSB duplex, and RT-ddPCR multiplex assay
| EDx standard (Cp/reaction) | RT-PCR (Ct value) | RT-ddPCR (copies/reaction) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| E Simplex | E-GUSB Duplex | |||||||||
| SARS-CoV-2 | SARS-CoV-2 | GUSB | SARS-CoV-2 | Rpp30 | GUSB | FA (%) | ||||
| Water | Total NA | Water | Total NA | Water | Total NA | |||||
| 1000 | 31.7 | NA | 31.3 | NA | NA | 1098 (1004–1192) | NA | NA | NA | NA |
| 1000 | 31.7 | NA | 31.6 | NA | NA | 1002 (916–1090) | NA | NA | NA | NA |
| 100 | 34.2 | 34.2 | 34.4 | 33.1 | 32.2 | 108 (80–140) | 94 (70–124) | 4531 (4338–4726) | 155 (123–192) | 38 |
| 100 | 34.7 | 34.4 | 34.6 | 33.6 | 32.2 | 114 (86–150) | 96 (74–124) | 4343 (4164–4523) | 115 (89–145) | 45 |
| 10 | 34.1 | ND | 36.3 | ND | 32.2 | 20 (10–34) | 5.6 (1.4–14.8) | 5028 (4830–5229) | 160 (128–196) | 3 |
| 10 | 34.5 | ND | 36.8 | ND | 32.1 | 12 (4–24) | 18 (8–32) | 4990 (4788–5194) | 152 (120–188) | 10 |
| 5 | ND | ND | ND | ND | 31.9 | 9 (2.6–21) | 9 (3.2–19.6) | 5254 (5054–5457) | 112 (86–142) | 7 |
| 5 | ND | ND | 37.3 | ND | 32.0 | 2.4 (0.2–11.8) | 3.2 (0.4–10) | 4942 (4761–5125) | 129 (103–159) | 2 |
| 5 | 35.2 | 35.6 | 36.9 | ND | 32.0 | 7.6 (2.2–17.8) | 11.6 (4.8–22.4) | 4818 (4635–5002) | 124 (98–154) | 9 |
| 5 | 35.2 | ND | ND | ND | 32.0 | 5.6 (1.4–14.8) | 10.2 (3.6–22.4) | 5256 (5041–5472) | 148 (117–186) | 6 |
| 2.5 | ND | ND | ND | ND | 32.1 | ND | ND | 4820 (4640–5020) | 122 (96–154) | |
| 2.5 | ND | ND | ND | ND | 32.2 | ND | ND | 5160 (4960–5380) | 106 (80–138) | |
| 2.5 | 35.3 | ND | ND | ND | 32.0 | ND | 3.4 (0.6–11) | 4840 (4660–5040) | 112 (86–142) | 3 |
| 2.5 | ND | 35.6 | ND | ND | 32.3 | ND | ND | 4860 (4660–5060) | 112 (86–144) | |
NA not applicable, ND not detected, FA fractional abundance of viral RNA calculated with respect to the GUSB concentration
*Gold standard assay [2]