Yes, Covid PCR Tests Are Still Accurate

At least 43,000 people received a positive lateral flow result then a negative PCR test. Here's what's going on

Covid PCR tests are usually considered the most reliable way to find out if an individual has the disease.

These lab tests have come under scrutiny in the last month, but an investigation into just one laboratory might just have found the root cause – meaning PCRs are still just as accurate.

Why are people doubting PCR Tests?

A private lab in Wolverhampton called Immensa was suspended on Friday from the NHS Test and Trace service after a processing error meant thousands of people may have received the wrong PCR result.

At least 43,000 people were falsely told they had not tested positive for Covid after the lab analysed their PCR tests, according to health officials.

The UK Health Security Agency found these results were incorrectly recorded between September 8 and October 12 predominantly in South-West England, although some tests also came from the South-East and Wales.

These people all tested negative on a PCR test after receiving a positive lateral flow test (LFT) result.

What happens next to those who received false negatives?

Test and Trace will be contacting those who were tested by the Wolverhampton lab in the last two weeks and they will be advised to take another test to make sure they are not infectious.

PCR tests are usually considered the most reliable form of Covid testing
aquaArts studio via Getty Images
PCR tests are usually considered the most reliable form of Covid testing

When did this problem start?

Reports that positive LFTs were being followed up with negative PCR tests started in the middle of September.

At the same time, the number of cases in the South-West began dropping from mid-September.

Scientists started calling for an inquiry days before the Wolverhampton lab found over fears the PCRs were no longer effective.

The government advice is for anyone with Covid-like symptoms to carry out an at-home LFT, and if the result is positive, it should be followed up with a PCR test.

If the PCR result is negative, the individual usually does not need to self-isolate.

PCR tests are considered more reliable and normally the ultimate way to detect Covid – so reports that they were producing inaccurate results left the scientific community panicking.

What is really behind these unreliable results?

In September, there were concerns LFTs were responsible or a new mutation of Covid was not being detected by PCR tests.

Scientists even thought that LFTs could be picking up on other viruses such as the common cold.

However, health authorities now seem to be blaming neither LFTs nor PCR tests for getting the results wrong, although the exact reason has not yet been confirmed.

On Friday, Will Welfare from UK Health Security Agency said: “There is no evidence of any faults with LFD or PCR test kits themselves and the public should remain confident in using them and in other laboratory services currently provided.”

Immensa boss Andrea Riposati also added: “We are fully collaborating with UKHSA on this matter. Quality is paramount for us.”

Why is this a major issue for Test and Trace?

The private lab which gave out the wrong results was actually awarded a £119 million contract four months after it was founded in May 2020.

The blunder with the test results will only add to further accusations against the government that it was not prepared for the pandemic when it struck last year.

In June, Test and Trace was also found to have lost track of nearly 600 million Covid tests.

How does this impact the UK’s Covid response?

Britain has just announced that it will be relying on LFTs rather than PCRs for fully-vaccinated passengers arriving in the UK from countries not on the red list.

This could signal a more general shift towards greater reliance on LFTs in the coming months.

The overall effect of letting approximately 43,000 people out of isolation when they may have been positive for Covid remains to be seen.