Sample pool tests

All testing and standard curve preparation was performed on the same GeneXpert system using the same module. Initially, each sample was tested without pooling and Ct values were used to determine the viral load. Each sample was then diluted in a pool of confirmed negative clinical specimens to simulate either three- and six-sample pools (corresponding to a three-and six-fold dilution, respectively). Due to a shortage of assay cartridges, only the six-sample pools were performed in triplicate and a limited number of samples were included in our panel. Each replicate pool was created independently.