Fig. 3.

Limit of detection analyses of respiratory samples positive for either delta (top panels) or omicron (bottom panels) by RT-qPCR for nine SARS-CoV-2 RATs. a test #1–5, b test #6–9. The log10 RNA copies subjected to the test of quantified samples on the x axis were plotted against a positive (+ 1) or negative (0) test outcome on the y axis. For readability of the figure, slight normal jitter was added to the y values. Blue (delta) and red (omicron) curves, respectively, show logistic regressions of the viral load on the test outcome; vertical dashed lines indicate log10 RNA copies subjected to the test at which 50% (LoD50) and 95% (LoD95), respectively, of the samples are expected positive based on the regression results. Significant differences for LoD50: test 2, 3, 4 and 7. Significant difference for LoD95: test 7