Re-introduction of confirmatory polymerase chain reaction (PCR) testing for positive lateral flow device (LFD) tests at assisted testing sites

From tomorrow (31 March), NHS Test and Trace is reintroducing confirmatory PCR testing for positive LFD tests conducted at all assisted testing sites, including schools and colleges. This means that all staff, pupils and students who get a positive LFD test, whether at home or supervised at their school or college, should get a confirmatory PCR. The PCR test should be booked immediately either online or by calling 119 and should be undertaken within 2 days.

Staff, students and pupils who had a positive LFD test result, and their close contacts and other members of their household, should self-isolate immediately in line with NHS Test and Trace guidance and while awaiting the PCR result. If the PCR test is negative, it overrides the LFD test and the staff member, pupil or student can return to school or college, and their close contacts can end their self-isolation.

In January, when the prevalence of the virus in England increased, NHS Test and Trace temporarily paused the requirement to do confirmatory PCR tests for positive LFD tests that were conducted at an assisted testing site. This followed advice from PHE that, when coronavirus (COVID-19) prevalence rates are high, the performance of LFD tests and PCRs are broadly comparable and expected to be indistinguishable when used at test sites, significantly reducing the need for routine confirmatory testing.

PHE and NHS Test and Trace have kept this pause under review. As prevalence of the virus in England is now low, confirmatory PCR testing will also help to minimise the chances of false positives.

All existing protective measures set out in the schools operational guidance and further education operational guidance remain important and the need for these is not lessened. A negative PCR or LFD result should not be read as a means to relax or ignore social distancing or other virus prevention measures intended to reduce transmission – rapid testing is an additional tool that contributes to reducing risk.

To increase our preparedness and heighten our defences against new variants, NHS Test and Trace has backed new technology, known as ‘genotype assay testing’, which could halve the time it takes to identify if a positive coronavirus (COVID-19) test contains a variant of concern. This will allow positive cases to be traced sooner and stop the spread of variants in the UK. Genotype assay testing is compatible only with PCR tests. The government has reintroduced confirmatory PCR testing for positive LFD test results in England to detect the maximum number of cases with variants. Confirmatory tests are used to validate the result of the initial rapid test.

Please see PHE’s blog on COVID-19: reintroducing confirmatory PCR testing for further information.