COVID-19: PCR confirmation of lateral flow testing is reintroduced

In 2020 and early 2021 anyone who received a positive COVID-19 lateral flow test was asked to confirm this with a PCR test. This guidance was paused in January but has now been reintroduced.

One of the main reasons for the reintroduction of confirmatory PCR testing is the government’s investment in a new technology known ‘genotype assay testing’, which can halve the time it takes to identify if a positive COVID-19 test contains a variant of concern. This technology is only compatible with PCR tests and therefore confirmatory PCR tests are being carried out to detect the maximum number of cases with variants.

What does this mean for me and my employees?

If an employee does a rapid lateral flow test at a test site or at home and the result was positive:

  • they and anyone they live with should self-isolate immediately
  • they should get a PCR test (a test that is sent to a lab) to confirm their result as soon as possible

Anyone with positive test should follow the NHS guidance in full, which can be found here.

If an employee tests positive within the workplace, implement your infection control procedures and ensure the employee returns home. Sanitise any areas that they may have visited thoroughly, recording that you have done so.

Depending on the circumstances of any positive tests identified by your workplace testing programme, you may be required to report COVID-19 infection to the Health & Safety Executive. Please contact the Citation Health & Safety advice line for help.

What are the different test types?

  • Lateral Flow Devices (LFDs) – simple devices that can be used at home, in workplaces and community testing sites. The results can be seen within 30 minutes of the test itself, similar to a pregnancy test.
  • PCR tests are sent to a laboratory with the results usually confirmed by text or telephone.

Both tests involve taking a swab of the inside of your nose and the back of your throat, using a long cotton bud.

Why has the guidance changed again?

As with any test, there are a number of factors that can impact results, such as how the sample is taken and also the accuracy of the test. Lateral Flow Devices have a high specificity, which means the number of false positives are extremely low – less than 1 in 1000 tests.

However, as the prevalence of COVID-19 reduces to low levels in the population, the chance of a false positive result increases – though still remains unlikely.

During periods of low virus prevalence, the risk of false positives can be mitigated by confirming a positive lateral flow test with another test – such as a PCR test performed in a laboratory.

This makes it highly unlikely that anyone would need to self-isolate unnecessarily, while ensuring the benefits of rapid testing to detect true positive cases and for confirming when people are not infected.

Confirmatory PCR testing was first put in place upon the introduction of rapid testing last year, but was temporarily paused in January, as the prevalence of infection was high, and it was highly likely that a positive LFD COVID-19 result was a true positive.

That meant PCR testing was reserved for those who had clinical symptoms.

There is thankfully now a much lower prevalence of the virus across the population, which is why PCR testing is being reintroduced to confirm all positive lateral flow results.

If you’d like to read more about the reasoning behind the reintroduction of confirmatory PCR testing, Public Health England have published an article exploring the issue, which you can find here.

How Citation can help

If you want to discuss the impact of workplace testing in your business, you can call Citation’s team of Health & Safety experts 24/7 on 0345 844 4848.

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