Figure 3
From: Sensitive detection and quantification of SARS-CoV-2 in saliva
Comparison of research RT-PCR (a) and ddPCR (b) results between nasal swab and saliva. (a) Dashed boxes indicate number of negative samples with Ct value of 45. The number of nasal swab specimens with Ct value of 45 for N1 and N2 was 68 and 69 respectively, whereas the number of saliva samples with Ct value of 45 for N1 and N2 was 69 and 68 respectively. There were 9 and 7 nasal swab samples that were negative for N1 and N2 respectively, but these patients were detected as positive for these targets in matched saliva samples. There were also 3 and 3 nasal swab samples that were positive for N1 and N2 respectively, but called negative for these targets in matched saliva specimens. Per CDC recommendations, a sample is called positive if either N1 or N2 are below the RT-PCR thresholds. (b) Dashed boxes indicate number of samples with readout of 0. The total number of negative samples with concentration readout of 0 for N1 in nasal swab and saliva specimens was 50 and 58 respectively, while the number of negative samples with concentration readout of 0 for N2 in nasal swab and saliva specimens was 28 and 40 respectively. The number of nasal swab negative but saliva positive results are 19 (N1) and 5 (N2) and the number of nasal swab positive but saliva negative results are 1 (N1) and 3 (N2).
