PMC

Comparison of calibration curves by laboratory, comparing all test panel runs.

Comparison of calibration curves for all test panel runs.

Consistency of results for negative and low viral load samples. Each solid line shows the results of a negative or low viral sample for one panel across labs. The plot includes all instances with a mean viral load less than or equal to 2 on the log-scale. The results deemed negative by the lab are shown as −4 on this plot. A dashed horizontal line at y = 1 is included for purposes of qualitative interpretation.

Variation in viral load values for patient samples. Each point gives the result from a specific laboratory for the indicated panel and sample number. The horizontal line at y = 1 corresponds to the threshold used to qualitatively interpret the findings as positive or negative. The numbers at the bottom of each plot indicate the number of laboratories that did not report a C_T value and interpreted the result as negative (zeroes are not shown).