To evaluate the colorimetric RT-LAMP assay, we needed to compare its sensitivity and specificity to a validated RT-qPCR method. We first used 95 RNA samples and performed RT-LAMP reactions using 1 μl of the isolated RNA in a reaction volume of 12.5 μl. We detected a red-to-yellow color change in 36 of the samples following an incubation of the reaction for 30 min at 65°C (Fig. 2A). To quantify the reaction, we used a plate scanner and measured the difference in absorbance (ΔOD) of the samples at 434 and 560 nm (corresponding to the absorbance maxima of the two forms of phenol red that were used in the assay as a pH-sensitive dye) at several time points. To visualize the data, we plotted the ΔOD values against incubation time and colored the time traces of individual samples according to the cycle threshold (CT) values obtained from the RT-qPCR test run in the clinical diagnostic laboratory (Fig. 2B). This RT-qPCR test was performed using a commercial diagnostic test kit containing a modified version of the E-Sarbeco primer set for the viral E gene suggested by Corman et al. (15) and 10 μl of RNA isolated with an automated platform (QiaSymphony or QiaCube).