Scientists have begun trialling rapid lateral flow tests across 200 schools in England in an effort to prove the accuracy and effectiveness of the controversial technology.
Students and staff will be offered weekly tests using lateral flow devices (LFDs). Half the participating schools will then offer daily tests to students who have come into close contact with known Covid-19 sufferers, to enable them to avoid quarantine, while the rest — the control group — will make such students quarantine for 10 days.
Researchers involved in the study hope the research will prove that the tests can effectively pick up cases of infectious disease, providing evidence to counter the pervasive scepticism surrounding the value of LFDs, which have been rolled out in large numbers since late last year.
“We’re trying not to be biased and find out the truth,” said Tim Peto, professor of medicine at the University of Oxford, who has been working with the government on the rollout of the tests. “We’re going to find out whether they miss things as the sceptics claim they do.”
The hypothesis is that schools where students take daily tests rather than quarantine will have increased attendance while keeping transmission to at least the same level as the “control” group.
Jon Deeks, professor of biostatistics at the University of Birmingham and a critic of the widespread use of LFDs, said the study was a “step in the right direction” to understanding the value of the tests.
But, he said a better study would be one comparing schools using lateral flow tests with others that do not.
“Seeing as we don’t know that this type of testing actually works, that’s sort of a missing question here,” Deeks added.
The government has spent over £2bn since the pandemic struck acquiring lateral flow testing kits, which are now being deployed in schools, care homes and across the community for twice-weekly testing.
But several scientists and testing experts have complained that only limited proof exists that these tests can spot cases of infection early and therefore reduce the burden of Covid-19.
Concerns had been raised that the tests were missing 20 to 60 per cent of active Covid-19 cases. In recent weeks, as the prevalence of Covid-19 has decreased in England, attention has turned to “false positives”.
Senior government officials were reported to have been concerned that positive test results were likely to be inaccurate in areas where the prevalence of the virus was low.
Ben Dyson, an executive director of strategy at The Department of Health and Social Care and one of health secretary Matt Hancock’s advisers, called for a “fairly urgent need for decisions” regarding “the point at which we stop offering asymptomatic testing” in a letter, the Guardian reported last week.
The report added that as few as 2 per cent of positive results may be accurate in places with low Covid-19 rates, such as London, where less than one in 500 people currently have the virus.
This contrasts with an official government presentation, seen by the Financial Times, saying that around 80 per cent of positive LFD results have been confirmed to be correct by gold-standard polymerase chain reaction (PCR) tests.
The presentation added that in the last two weeks, 5.5m LFD tests, made by US company Innova and taken at schools and colleges, had produced 4,005 positive results. Of the positive tests that were then verified by PCR, almost three quarters were confirmed to be accurate.
The data suggested a “false positivity” rate of 0.02 per cent in schools, according to Alex Selby, an independent mathematician who has been studying government figures on LFDs.
The DHSC said: “There is clear evidence that rapid testing detects cases quickly, meaning positive cases can isolate immediately, and recent figures show for every thousand lateral flow tests carried out, there is fewer than one false positive result.”