Figure 4
(a) Calibration curve using Influenza A DNA template ranging from 101 to 109 copies per reaction; error bars represent standard deviation of at least triplicates (b) Serial dilutions of a SARS-COV-2 positive sample with a reported Ct value of 19 were measured with the qcLAMP method. (c) Correlation (R2 = 0.99) between the qcLAMP time-to-positive results and the viral RNA concentration based on a tenfold serial dilutions. (d) Scatter plot of the Ct values (ranging from 16 to ~ 37) for 38 positive samples versus the qcLAMP time-to-positive (ranging from 12.5 to 23 min). qcLAMP measurements were performed in different days within 3 weeks using stored (− 80 °C) RNA samples. Only one point was missed by qCLAMP in the first run corresponding to a Ct of 35. (e) Diagnostic results of SARS-CoV-2 qcLAMP assay-evaluation with 89 clinical samples including 38 COVID-19 positive and 51 negative. An overall sensitivity of 97% (95% CI: 93–100), specificity of 100% and negative likelihood ratio of 0.026 (95% CI: 0.004–0.182) were calculated.
