@Tibtom
Or they could scrap them as having no value at all. A test with a 97% chance of returning a negative when it should be positive in order to prevent the level risk of transmission from asymptomatic positives which is not statistically different from 0% is worse than useless and likely to increase spread amongst symptomtic individuals. Not to mention the hundreds of thousands of pupils who will miss school each week from false positives. Mass testing with LFT is totally unethical bordering on the criminally negligent.
A group of experienced scientists has issued a statement supporting the use of lateral flow tests in the battle against Covid.
They say the rapid devices have identified 27,000 infected people in the UK who would not otherwise have had to self-isolate.
The findings of a recent report suggested the tests were inaccurate and potentially harmful.
But the scientists say that report was flawed and confused.
Signatories to the statement include Prof Calum Semple, professor of outbreak medicine and child health, from the University of Liverpool, Prof Sir John Bell, regius professor of medicine at the University of Oxford, and Dr Susan Hopkins, interim chief medical adviser from Public Health England.
They reject the accusation, in a report by Prof Jon Deeks, Dr Angela Raffle and Dr Mike Gill on 10 January, that lateral flow tests (LFT) will cause harm, saying there is no evidence for the "irresponsible" claim.
And they say the tests are fast, easy to use and an essential tool in the current epidemic.
The scientists go on to explain that the report confused the role of PCR tests and lateral flow devices.
PCR tests, which the NHS uses to test people with symptoms and are sent off to a lab for the results, can detect dead virus as well as viable virus.
That means people can test positive for weeks after the point they are actually infectious, or capable of passing the virus on to others.
As a result, only a subset of people testing positive with PCR tests are actively infectious.
Lateral flow tests, however, are designed to detect live virus in people with no symptoms who are highly infectious. Results are available in 30 minutes which means those who test positive can isolate quickly.
The Deeks report said a Liverpool pilot of lateral flow tests had "missed infection" in 60% of people - but the scientists say that data has been misinterpreted.
'No gold standard'
Neither PCR or lateral flow is a perfect test, but "treating PCR as a gold standard of infectiousness" is a mistake, they say.