The government is rolling out mass Covid testing - but how reliable are lateral flow tests?
As new ‘lateral flow’ coronavirus tests are made available through mass testing programmes across the country (including Sunderland), many are asking whether the kits – which can give a result in under an hour – are reliable.
So far the tests have been used in Liverpool’s pilot, where they have been available to people who live and work in the area and do not have symptoms.
They are currently being rolled out to nearly 70 local council areas, with "a load more” expected to sign up in the near future.
But can they really solve the UK’s pandemic woes?
Here is everything you need to know.
How does the test work?
Lateral flow tests can give a result in around 20 minutes, and do not require samples to be sent to a lab for analysis, though must be conducted at a dedicated testing site by trained personnel.
The tests – which look similar to a pregnancy test – are taken in much the same way as the more common polymerase chain reaction (PCR) test, with a swab taken from the nose or back of the throat.
They are designed to be intuitive and require minimal training to operate; Public Health England are looking at how the test could be self-administered in the future.
Anyone who tests positive must self-isolate along with their household immediately and their contacts will be traced. Those who test negative will need to continue to follow all national guidance.
Are they accurate?
The accuracy and speed of the tests means they can be used to test a higher proportion of asymptomatic people.
That enables authorities to identify and isolate more people who are at high likelihood of spreading virus, thus breaking the chain of transmission. But are they really that reliable?
The Government has placed its faith in a test manufactured by Innova, a California-based company that is reportedly shipping over a million kits to the UK every day.
The Department of Health and Social Care say the tests have an accuracy of 99.6 per cent, and are “highly reliable, sensitive and accurate in multiple settings.”
Susan Hopkins, Chief Medical Adviser, NHS Test and Trace, said: “These tests are proving to be accurate and reliable. And, importantly they’re able to detect COVID-19 in people without symptoms who could unknowingly be passing the virus onto others.
"We are confident that these new tests, which have been rigorously evaluated, will make a real difference in how we protect people.”
How likely is a false negative?
Some experts dispute the tests’ effectiveness.
Professor Sebastian Johnston of Imperial College London told The Guardian the Government were giving the impression that “all lateral flow antigen tests have high-sensitivity following extensive clinical testing. This is very far from the truth.”
Some trials of the lateral flow test have found it to be much less accurate than the government say it is, including a trial in a community test centre which picked up just 58% of Covid-19 cases.
Professor Jon Deeks, an expert in assessing Covid-19 tests, told The Guardian the tests “may give more false positives than true positives when used in mass screening.”
“I am really concerned that people are not given information to understand what the results mean,” he added. “A negative test indicates your risk is reduced to between a quarter and one half of the average, but it does not rule out Covid.
"It would be tragic if people are misled into thinking that they are safe to visit their elderly relatives or take other risks. The government’s plan is both wrong and dangerous.”
A version of this article originally appeared on our sister title, the Sunderland Echo