There's 'absolutely no chance' the Government's new 15-minute coronavirus tests are accurate enough to get life back to normal, a leading expert warned today.
It emerged last night ministers are set to buy up to 200million of the £5 kits, which are made by US company Innova and give a 'yes' or 'no' result in a quarter of an hour.
They have been heralded as a key to unlocking the economy when the second lockdown ends, allowing people with a negative result to visit the theatre, cinema or a sports event.
But Professor Jon Deeks, a biostatistician from the University of Birmingham, warned they could be 'dangerous' if Brits who test negative see it as a green light to visit elderly grandparents.
Trials of the devices by Public Health England and Oxford University found they could detect up to three in four positive cases.
But, after poring over the data, Professor Deeks said they could actually miss half of all infections when they are used in real world scenarios rather than in hospitals by a trained nurse - a finding he described as 'worrying'.
Professor Deeks, who is also head of the Biostatistics, Evidence Synthesis and Test Evaluation Research Group at the university, said on Twitter: 'Between one in two and one in four current cases of Covid-19 will be missed. Other tests are better.
'Those getting negative results need to know Covid risk is reduced, but they could still have Covid, and get Covid tomorrow or next week. Harmful for them to think they are Covid-free - especially if they now cuddle their granny.
'How on earth can we get to a safe 'test-and-release' strategy with a test which can miss up to one in two cases? IMHO [In my humble opinion] ABSOLUTELY NO CHANCE!'
A rapid Covid test which costs just £5 could finally allow Britons back into concerts and sports events. Pictured: Mass testing site in Liverpool
Professor Jon Deeks, a biostatistician from the University of Birmingham, warned the could be 'dangerous' if Brits who test negative see it as a green light to visit elderly grandparents
There are plans to buy more than 60million rapid tests a month from January, according to The Daily Telegraph, with 192 million purchased in total by March.
The tests are one of those at the heart of the Operation Moonshot pilot and could see the kits used in towns and cities across the UK to help the government get on top of the pandemic by the spring.
The Innova kits are technically up to 95 per cent accurate, but only when dealing with people who have a high viral load - which makes people most infectious.
Their accuracy drops sharply when people have low levels of the virus in their bodies - which can often be the case with young and healthy asymptomatic people who go on to become unwitting super-spreaders.
The Innova test was trialled in two studies by Oxford University and PHE.
One saw a trained nurse give the test to hospitalised Covid-19 patients and the other was done by an untrained volunteer at a PHE testing centre who followed written instructions.
Operation Moonshot is the Government's plan to get millions of people tested and given a result on the same day.
Tests would be routinely given to hospital staff, carers and swathes of the workforce to try and jump-start the economy.
But there have been serious doubts about whether Number 10 is capable of pulling it off.
Currently the Department of Health has a testing capacity of around 500,000.
And just 15 per cent of people who have an in-person test currently get a result within 24 hours.