The PCR test is reliable and effective. Lighthouse laboratories that will undertake the processing of the majority of the tests have been reviewed by experts as part of their set up and each has a clinical virology lead. Like any diagnostic test however, there is always the small possibility of a false negative or a false positive result.

We do not have a method for collecting data for false positive or false negative results arising from testing within the national testing programme, however ONS data on the current tests show they are very specific and the risk of false positives is extremely low.

Published academic evidence from the UK and internationally demonstrates that self-administered test kits can be just as effective as clinician-administered tests in securing a good sample.

Guidance has been produced and published:
(https://www.gov.uk/government/publications/sars-cov-2-rna-testing-assurance-of-positive-results-during-periods-of-low-prevalence/assurance-of-sars-cov-2-rna-positive-results-during-periods-of-low-prevalence)
that allows laboratories to provide assurance of positive SARS-CoV-2 RNA results during periods of low prevalence and is being implemented.

Positive test results should be treated as accurate and the patient should isolate until at least 10 days after their symptoms commenced and their fever has resolved according to the national guidance.

Information from ONS on test specificity and false positives following a Covid-19 infection survey is available here - https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/methodologies/covid19infectionsurveypilotmethodsandfurtherinformation#test-sensitivity-and-specificity

A summary for round 1 of the Quality Control for Molecular Diagnostics EQA for the PCR test can be found here: https://pubmed.ncbi.nlm.nih.gov/32672149/

Department of Health and Social Care