Positive results from UK single gene testing for SARS-COV-2 may be inconclusive, negative or detecting past infections

Neil, Martin

The UK Office for National Statistics (ONS) publish a regular infection survey that reports data on positive RT-PCR test results for SARS-COV-2 virus. This survey reports that a large proportion of positive test results are based on the detection of a single gene rather than on two or more genes as required in the manufacturer instructions for use, and by the WHO in their emergency use assessment. The proportion of positives called on single genes increased from mid-November to mid-December 2020, suggesting a shift in testing policy coincident with the reported significant increase in transmission of the new variant B1.1.7, and again starting January 2021. Without diagnostic validation of the single gene call, for both the original and the B1.1.7 variant it can only be assumed that, in the absence of confirmatory testing, many of the reported positive results may in fact be inconclusive, negative or from people who suffered past infection for SARS-COV-2.