Indeterminate COVID results

The polymerase chain reaction (PCR) test for the detection of SARS-CoV-2 in respiratory specimens is an essential tool in screening and diagnosing COVID-19¹. Clinical virology laboratories often make use of a diverse repertoire of testing platforms with varying performance characteristics. The high analytical sensitivity of PCR assays often results in low-level detections. For very low-level detections, when the Ct value of a PCR test is above a certain threshold², and not all the analytical targets are detected, the result is inconclusive or “indeterminate” (IND). It has been estimated that up to 5% of SARS-CoV-2 PCR results may be inconclusive³. Up to 40% of these are subsequently shown to be “negative” with repeat testing⁴. This highlights the fact that patients with IND results should be managed as potentially infectious (Person Under Investigation [PUI]) until a definitive diagnosis can be made.