Public health chiefs today warned easing lockdown before NHS Test and Trace is running at 'full speed' could result in the UK 'hitting the brakes' too late to stop a second wave of coronavirus.
The Government's test and trace system launched last week but it went live without the key NHSX contact tracing app while some staff have complained they have not got any work to do, passing the time by watching Netflix or playing with their dog.
But Boris Johnson is pushing ahead with his plans to loosen draconian restrictions, with primary schools now having started their phased return while non-essential shops should start to reopen later this month.
Experts believe a fully functioning test and trace programme will be critical if the UK is to avoid a spike in infections as life gets back to normal.
Local health bosses are concerned that easing measures now before test and trace has shown itself to be effective could have disastrous consequences.
They said the data from test and trace should help inform decisions and that without a full picture the Government may not actually know the scale of a fresh outbreak.
That could mean that by the time ministers realise they need to reverse lockdown loosening it could be too late and the UK could have 'spun off the road and be over the cliff-edge'.
Downing Street today continued to refuse to publish any of the data showing how effective the scheme has been since its launch.
Boris Johnson, pictured in Number 10 yesterday, is pushing ahead with easing lockdown despite NHS Test and Trace only launching last week
The NHS Test and Trace programme launched last week but ministers are under pressure after failing to reveal how many people have so far been contacted
Test and trace requires people with symptoms to self-isolate and get tested. If they test positive their close contacts are then tracked down and also told to self-isolate.
The system is designed to break the chain of transmission as quickly as possible in order to squash potential outbreaks and stop them from escalating.
Lisa McNally, public health director at Sandwell Council in the West Midlands, said she was surprised the lockdown had been eased before the test and trace system was at 'full speed'.
She told BBC Radio 4's Today programme: 'This system is certainly up but I'm not sure about running.'
She continued: 'I don't think I'm particularly surprised, to be honest, that this system isn't running effectively in a few short days - it was never going to be, it is an enormous task.
'What surprises me, I guess, is that we are moving ahead so quickly with easing lockdown before the system is at full speed.
'We need to allow time to assess how things are going, get this system up to speed.
'To be honest with you, I'm concerned that by the time we realise we need to hit the brakes, we will have spun off the road and be over the cliff-edge.'
She predicted the UK could be 'going back to a place we really don't want to be, which is where we were at the end of April' in terms of the number of coronavirus-related infections and deaths if test and trace does not prove to be effective.
Ministers are facing growing criticism over their refusal to publish data showing how many people have been contacted by NHS Test and Trace so far.
Number 10 would only say today that the numbers will be released 'shortly' once the data has been verified.
Told that without the statistics it is impossible to know if the system is working and therefore it will be hard for the public to have confidence in it, the Prime Minister's Official Spokesman said: 'I certainly understand the desire for data to be published showing precisely how it is working.
'But equally it is important that when we do put that information into the public domain it has been properly validated.
'We are working on that. We understand the need for transparency and as I say we will be providing weekly updates on test and trace shortly.'
NHS Test and Trace has suffered numerous set backs since it went live with many staff complaining that they have not got any work to do.
One contact tracer today said he had spent four shifts playing with his puppy and claimed that more than 80 per cent of staff were idle on Wednesday afternoon.
The man said: 'It’s really frustrating. They’re throwing thousands or even millions of pounds away, all of the time I’m sat here doing basically nothing.
'I sit next to my laptop, reading newspapers and looking after my new puppy. We were told we need to be ready at a moment’s notice, but we’re sat here watching.'
It comes after Mr Johnson pledged yesterday to process all coronavirus tests within 24 hours by the end of June.
However, it subsequently emerged that the target will not include postal kits while tests sent to care homes may also not be included - approximately one third of the daily total.
Experts believe tests must be processed within 24 hours so that the contacts of people who test positive can be swiftly identified and told to self-isolate in order to prevent the spread of the deadly disease.
The fact that the PM's 24 hour pledge does not appear to be a blanket guarantee is likely to prompt a backlash amid fears delays in processing tests could hamper efforts to prevent a second wave.