Application of digital PCR to determine the reliability of Xpert Xpress SARS-CoV-2 assay with envelope (E) gene negative and nucleocapsid (N2) gene positive results.

This study used digital polymerase chain reaction (dPCR) to determine whether envelope (E) gene-negative and nucleocapsid (N2) gene-positive (E-N+) results obtained with the Cepheid Xpert Xpress SARS-CoV-2 assay are reliable. Using droplet digital PCR results as a reference, 18 of 22 E-N+ samples with a low viral load (81.8%) were identified as true positives.