COVID-19 Testing Suspended at Private Lab After False Negatives

Nicky Broyd

October 15, 2021

Analysis of COVID-19 PCR tests has been suspended at a private laboratory in Wolverhampton after people received false negative results following positive lateral flow tests (LFDs).

The UK Health Security Agency (UKHSA) said around 43,000 of 400,000 samples, mostly from the South West of England between 8 September and 12 October, may have resulted in incorrect results.

England's Test and Trace service has suspended testing operations provided by Immensa Health Clinic Ltd following an investigation after reports of testing anomalies. It stresses that there are no issues with the test kits themselves.

Test and Trace is contacting people who may have been affected for re-testing.

Continuing Investigation

Dr Will Welfare, public health incident director, UKHSA, said: "We have recently seen a rising number of positive LFD results subsequently testing negative on PCR. As a result of our investigation, we are working with NHS Test and Trace and the company to determine the laboratory technical issues that have led to inaccurate PCR results being issued to people. We have immediately suspended testing at this laboratory while we continue the investigation.

"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. If you get a positive LFD test, it’s important to make sure that you then get a follow up PCR test to confirm you have COVID-19. If you have symptoms of COVID-19, self-isolate and take a PCR test."

Immensa CEO, Andrea Riposati, said: "We are fully collaborating with UKHSA on this matter. Quality is paramount for us. We have proudly analysed more than 2.5M samples for NHS Test and Trace, working closely with the great teams at DHSC and UKHSA. We do not wish this matter or anything else to tarnish the amazing work done by the UK in this pandemic."

Unanswered Questions

Commenting via the Science Media Centre, Prof Sheila Bird, formerly programme leader, MRC Biostatistics Unit, University of Cambridge, said some things were still unclear:

"Did the laboratory’s internal quality control fail to signal?

"Did inter-laboratory quality-control fail to signal?

"Identification was via PCR-adjudication of LFT-positive tests (and journalists' reporting): however, does the “problem” affect PCR tests done for persons without LFT-positive antecedent, who include citizens who have developed symptoms; who have been identified as close contacts of index infected persons and are following advice to seek immediate PCR; or are international travellers arriving into, or back into, the UK?

“Hence, the further information from UKSHA should identify the implicated laboratory’s weekly share of the PCR-testing in England in a range of specific contexts such as those listed above; together with its results per-context per week (versus in comparable other laboratories) so that trigger-points for identification of when/if the problem affected different PCR-contexts."

International Travel

Also announced today was a start date for lateral flow tests replacing day 2 PCR tests for international arrivals.

The changes come into force on 24 October and tests can be booked from 22 October.

Passengers will have to upload a photo of their private, paid for, tests to verify their results.

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