Question to the Department of Health and Social Care:

To ask Her Majesty's Government what estimate they have made of the percentage of COVID-19 polymerase chain reaction tests that have resulted in a false positive.

In June 2020 the Scientific Advisory Group for Emergencies published a briefing paper on the impact of false positives and false negatives in the United Kingdom’s COVID-19 reverse transcription polymerase chain reaction (RT-PCR) testing programme. A copy of the briefing paper is attached.

The briefing paper states that the United Kingdom operational false positive rate is unknown, and an attempt has been made to estimate the likely false-positive rate of national COVID-19 testing programmes by examining data from published external quality assessments (EQAs) for RT-PCR assays for other ribonucleic acid viruses carried out between 2004-2019. Results of 43 EQAs were examined, giving a median false positive rate of 2.3%.