Table 2.
Evaluation of 49 patients (101 swabs) with discordant COVID-19 testing and confirmatory testing results
| Swab 1 (n = 49 swabs) | Swab 2 (n = 49 swabs) | Swab 3 (n = 3 swabs)c | |
|---|---|---|---|
| NP swab in UTM (%) | 29 (59.2) | 32 (65.3) | 2 (66.7) |
| Deep nasal turbinate swab (%) | 20 (40.8) | 9 (18.4) | 1 (33.3) |
| Oropharyngeal swab (%) | 0 | 8 (16.3) | 0 |
|
Original swab test resulta (E gene Ct median; range) (RdRp gene Ct median; range) |
49 negative |
46 positive 3 negative (19.5; 13.0–35.5) (22.4; 16.2–37.8) |
3 positive 0 negative (13.9; 12.5–24.7) (16.5; 14.8–28.0) |
|
Positive result on E gene assayb (Ct range) |
5/49 (34.1–37.9) |
0/3 | ND |
|
Positive result on CDC N1 assayb (Ct range) |
2/49 (32.7–35.9) |
0/3 | ND |
|
Positive result on CDC N2 assayb (Ct range) |
5/49 (33.2–38.8) |
0/3 | ND |
Ct cycle threshold (cycles), E envelope, LDT laboratory developed test, ND not done, NP nasopharyngeal, RdRp RNA dependent RNA polymerase, UTM universal transport media
aTesting done using E gene/RdRp gene LDT SARS-CoV-2 rtRT-PCR
bRepeat testing conducted only on negative swabs to evaluate for false-negative results
cOnly 3 of 49 patients had a third swab done