The government has denied it is planning to scale back rapid coronavirus testing after reports claimed senior officials are concerned about false positives.
Ministers have spent billions of pounds on making lateral flow tests (LFTs) widely available nationwide, with Boris Johnson urging everyone in England to take two a week.
But senior advisers are concerned that as few as 2% to 10% of positive results may be accurate in areas with low COVID rates such as London, The Guardian reports.
Emails seen by the newspaper claim to show one of Health Secretary Matt Hancock’s advisers pressing for “fairly urgent decisions” on the “point at which we stop offering asymptomatic testing”.
But a government spokeswoman insisted that rapid testing “is an essential tool to control the spread of the virus as restrictions ease”.
She added: “Rapid testing detects cases quickly, meaning positive cases can isolate immediately, and figures show that for every 1,000 lateral flow tests carried out, there is fewer than one false positive result.”
According to reports, executive director of strategy at the Department of Health Ben Dyson claims that in London, where COVID-19 infections are low, a positive LFT result is at best 25% accurate – and at worst 2% accurate.
It is less likely to be accurate if the test is self-administered, he said.
Professor John Simpson, head of Public Health England’s public health advice team, said he is “a little concerned” about the “evidence needed to justify extending testing in the way proposed”.
The efficacy of rapid LFT tests has been the subject of debate for months, with some experts claiming the government is only endorsing them because they invested in billions of them earlier on in the pandemic.
Robert Dingwall, a professor of sociology on the government’s SAGE committee, previously told Sky News they are “pretty useless”.
“These tests miss people with early infections, so they are not really any kind of solution,” he said.
“The government has bought a huge stockpile of these tests and something has to be done with them.”
Scientists say that the number of false positive from rapid tests increases as outbreaks shrink.
This is because LFTs continue to produce similar numbers of false positives, even if the level of true positives is going down.
The experts say that false positives are causing people to miss work and education unnecessarily and that forcing people to self-isolate until they get a negative laboratory-verified PCR test is unfair.
Currently people in England can get two rapid tests a week – from their workplace, school, college or local testing site.
Packs of tests are also now available for collection at pharmacies and libraries – or for home delivery.