Top doctors have branded the Government’s test and trace programme a “national disgrace” that could lead to a second wave of cases.
The system aims to find out how and where coronavirus is spreading by testing people with symptoms.
Experts have identified 17 possible symptoms but only those with one out of three are to be tested.
These are a fever, cough or loss of taste or smell – which chief medical officer Chris Whitty says covers “95 per cent” of cases.
But other medics have rubbished his claim because those with other widely reported symptoms such as tiredness will miss out.
It means many could have the virus without knowing and pass it on.
Boris Johnson has also come under fire for saying he thought the list of symptoms was bigger than it was.
Asked about it in a TV briefing on Thursday, a clearly confused PM replied: “I thought we were listing more, but anyway...”
GP Nick Summerton called Mr Johnson’s failure “bewildering” and the Government’s approach as “haphazard and amateur”.
And he said of Professor Whitty’s claim: “It is nonsense. He’s just made it up, basically. I don’t know what evidence he was using.
“Chris Whitty was trying to make out that the public couldn’t keep more than three symptoms in their mind.
“There is an arrogance among senior politicians and their advisers that is dangerous.
"We really don’t want a second peak but there is a real risk of this if we build tracing contacts on poor foundations.”
The test and trace system launched last week but has been delayed amid problems recruiting 25,000 contact tracers and technical issues with the app.
Dr Summerton, who consulted on the app in April and takes calls from hundreds of people with Covid symptoms every day, claimed the policy has been rushed out too quickly and failure to widen the symptoms list risked missing up to 50 per cent of cases.
He went on: “There were three things they needed to do before rolling this out: get testing ramped up – testing fewer than 100,000 a day is inexcusable now.
"If I was in that position, I would resign. I’d be embarrassed I hadn’t done the job I was employed to do.
“They need to widen the symptoms they’re listing. And they need a way of dealing with people who have a false negative result.
"About a third who are tested are told they haven’t got coronavirus when they actually have.
“Track and trace is becoming a shambles, just like testing has been a shambles. The whole thing is an embarrassment. It’s a disgrace.”
Dr Sarah Jarvis, a GP of 30 years and clinical director of Patientaccess.com, said: “We have to look at the most common symptoms.
"Among the patients I’ve seen who ended up testing positive, profound tiredness and muscle ache has been common.
“It would be worth considering adding sudden aches and pains to the list.”
Dr Jarvis is concerned about the effectiveness of test and trace in the wake of Dominic Cummings breaking lockdown to drive to Durham while having symptoms.
She said: “One of the real issues is whether people will do what they are asked if they are told they have to self-isolate.
“Matt Hancock standing up and saying it’s your civic duty when in the previous breath he had defended Dominic Cummings is hypocrisy.
“I think the trust of the British people and their ability to act on behalf of the greater good has been severely eroded in the last week.”
Prof Martin Marshall, chair of the Royal College of General Practitioners and a London GP for 30 years, said: “The problem is, in the early days of the pandemic a policy was devised around patients in hospitals.
"That’s why there was such a narrow definition around coughs and fevers.
“We have to think more broadly about the different ways in which it presents.”
Shadow health secretary Jonathan Ashworth said: “A test, trace isolate regime is crucial to safe easing of lockdown but Boris Johnson doesn’t seem to understand how the system is going to work.
“After a week in which he has undermined pubic health messaging by standing up for Dominic Cummings, it’s vital government explain fully how test and trace will work.”
The Department of Health said: “We have been guided by the best available evidence from world renowned scientists.
“We have successfully launched the NHS Test and Trace, to help identify and control coronavirus, reduce the spread of the virus and save lives.
“Backed by the rapid expansion of testing and 25,000 dedicated contact tracers, we are now able to offer anyone with symptoms a test, and trace the contacts of those testing positive to prevent further transmission.
“Those with symptoms and their contacts must self-isolate to protect others from the virus and allow safe and gradual lifting of lockdown.”