Diane Schofield takes a lateral flow test as she arrives at the Aspen Hill Village care home in Hunslet, Leeds.
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LONDON — A battle has broken out in the U.K. over the use of rapid coronavirus tests — known formally as “lateral flow tests.”
A heated debate is taking place over just how accurate they are at detecting Covid-19 cases, and whether they should be rolled out as a cheaper and faster way to carry out mass testing.
The tests can be self-administered and detect current Covid-19 infection, with results usually within 30 minutes. They involve taking a swab from both nostrils, but not the throat, and can be processed without laboratory equipment.
The British government, which wants to see lateral flow tests rolled out to more settings such as schools, say the tests are accurate and reliable and allow for the regular testing of people who might have the virus but are asymptomatic.
But the tests have divided the scientific community, with critics saying that the tests are less accurate than PCR tests, which are still widely seen as the “gold standard” in terms of sensitivity and accuracy (although the results tend to take longer than 24 hours), and could lead to multiple false negative results.
The government is keen to expand testing regimes (in a strategy dubbed “Operation Moonshot”) as it could allow for a speedier exit from a third national lockdown that’s damaging the British economy further after a year of disruptions.
Most infectious Covid cases
A preprint of a government-funded study by the University of Oxford was published on Thursday which concluded that “lateral flow devices detect most infectious Covid-19 cases and could allow a safer relaxation of the current lockdown.”
The study also confirmed that the more virus detected in the nose and throat (known as the viral load), the more infectious the individual is: “This is the first time this has been confirmed in a large-scale study and explains part of why some people pass Covid-19 on and others do not,” the study noted.
As such, people with higher viral loads are more likely to pass the infection on to others, making these infected individuals the most important to detect, so they can be isolated in order to reduce onward transmission.
The wider use of lateral flow tests could help pick up more of these highly infectious individuals that transmit the virus more easily, the study said.
“Modelling suggests that lateral flow devices would identify individuals responsible for 84% of transmissions using the least sensitive of four (lateral flow) kits tested, and 91% using the most sensitive,” the study said, although it recognized that such tests are less accurate than PCR tests.
“Covid-19 tests that are less sensitive than the standard PCR but, easier to make widely available, such as lateral flow tests, could be a good solution to ensuring those who are highly infectious are able to know they need to isolate more quickly and could allow an easing of lockdown restrictions.”
“They would also allow more people to be tested yielding immediate results, including those who do not have symptoms and people at increased risk of testing positive, for example, because of their work or having been a contact themselves.”
Tim Peto, a professor of Medicine at the University of Oxford and senior author on the study, said that “we know that lateral flow tests are not perfect, but that doesn’t stop them being a game changer for helping to detect large numbers of infectious cases sufficiently rapidly to prevent further onward spread.”
The U.K. government had planned to roll out lateral flow tests in schools to conduct daily testing for coronavirus among pupils aged 11 to 18, in a bid to reduce the number of kids and young adults having to stay at home and self-isolate if they came into contact with a positive case.
However, the plan was shelved as the majority of schools took lessons online with a third lockdown being implemented due to a rapid rise in infections.