(A) Skipping a prior RNA isolation step, pharyngeal swab samples were subjected to the RT-LAMP assay either directly (left) or after 5 min of heat treatment at 95°C (right). For each sample, scatter plots are used to compare the swab–to–RT-LAMP assay results (ΔOD values) with the results of RT-qPCR (CT values). The measurement time point was 30 min after the start of the 65°C incubation. (B) Shown is the sensitivity (right) and specificity (left) of the swab–to–RT-LAMP assay [derived from the data in (A)] using the decision threshold indicated by the horizontal gray line in (A). Specificity and sensitivity values (thick lines) are shown with their 95% confidence intervals (boxes) as in Fig. 3, with blue indicating the direct swab–to–RT-LAMP assay and red indicating the hot swab–to–RT-LAMP assay. (Also see table S3).