Sunday, November 29, 2020

Scepticism at rapid ‘Direct-Lamp’ test being rolled out across NHS

Scepticism at rapid ‘Direct-Lamp’ test being rolled out across NHS

A new higher-speed Covid-19 test that is key to the government’s “moonshot” testing programme is facing mounting scepticism from leading scientists ahead of the publication of an official report into its accuracy.

The “Direct-Lamp” test, in which the government has invested at least £323m, was originally touted as a breakthrough technology. But questions have been raised about its accuracy, with one trial showing that it detected about 20 per cent of active infections.

The recently developed test, produced by Sussex-based diagnostics company OptiGene, has been rolled out across many NHS Trusts as the government looks to increase the testing of asymptomatic staff.

Concerns about the risks posed by Direct-Lamp tests were raised this month on a conference call arranged by the Clinical Virology Network, an advisory group which co-ordinates virology research between UK laboratories.

William Irving, professor of virology at Nottingham university and a CVN representative, said scientists involved in the test’s pilot studies had raised questions about its “sensitivity”, or ability to detect Covid-19 when it is present.

“At the last meeting two weeks ago we discussed concerns around the Lamp test,” he said. “The data suggested the tests had a sensitivity of below 50 per cent — and in some cases 20 per cent.”

The government disputed the claims and is throwing its weight behind the technology in spite of the concerns.

The department for health and social care (DHSC) said it was “incorrect” to claim the Direct-Lamp tests were low sensitivity. “A recent pilot showed overall sensitivity of nearly 80 per cent, rising to over 96 per cent in individuals with a higher viral load,” it said.

The DHSC added that it was in the “final phase” of publishing validation data from Birmingham university and eight other laboratories that it believes “will address any remaining concerns”.

OptiGene, which develops rapid diagnostics for veterinary diseases, announced in April that it had created a Covid-19 test that worked from “swab-to-result in less than 20 minutes”. The company claimed the test was “as sensitive” as the “gold-standard” benchmark PCR laboratory test, although the OptiGene test’s instructions for use state its sensitivity against PCR ranges from 55-100 per cent.

In early November, scientists from Greater Manchester’s mass testing expert group (MTEG) sent a letter to the chair of the region’s testing strategy group, first reported by the Guardian, raising significant concerns about the accuracy of the OptiGene test.

They said the pilot they had conducted showed the tests had “low sensitivity” of 46.7 per cent, and that they did “not feel the data supported the investment in the large scale rollout of Direct RT-Lamp saliva testing” in hospitals or care homes.

Last week, amid mounting concerns over the test, Dr Veronica Fowler, the scientist who has led the development of the Lamp tests, presented at a webinar for virologists and lab staff to confront the concerns from some academic quarters.

During the event, which was hosted by the British Infection Association, Dr Fowler said that “what sets Direct Lamp apart . . . is that it has this unique case for identifying really the immediately pre- and infectious people”.

However, the part of the webinar that examined data around the accuracy of the test has since been redacted.

Prof Irving said that the hypothesis put forward by Dr Fowler that Lamp picks up the more infectious cases by amplifying larger fragments of the disease in test samples, while ignoring non-infectious smaller debris, was “attractive” but she “didn’t show enough evidence to support it”.

A person with knowledge of the validations process said that virologists at both Manchester and Southampton hospitals had serious concerns. They said that some of the positives missed by the OptiGene Lamp tests “were incredibly positive by PCR” and that the individuals in question had clear clinical symptoms. 

“In a hospital like Southampton, where you have significantly vulnerable patients such as transplant, severe trauma, cancer patients, just one member of staff who remains at work, believing themselves to be negative, would have a devastating effect,” they said.

Many argue that high-speed tests that are less sensitive do have an important function for testing high-risk groups and finding asymptomatic individuals. However, it is not clear to some how Direct-Lamp technology improves upon the existing arsenal of antigen tests being used for this purpose.

One leading biomedical researcher involved in test validations for Public Health England said he had not seen any compelling data on the technology. “We can’t understand why the government is so excited about Lamp,” he said. 

Optigene did not respond to a request for comment.

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