A contact tracer working on the NHS Test and Trace coronavirus scheme says she has not been asked to speak to anyone since beginning work last week.
The clinician told the BBC's Victoria Derbyshire she had worked 38 hours but had yet to make a single phone call and spent the time watching Netflix.
"It's frustrating to know that I'm sat idle when there's people that need contacting," they said.
The government said this does not reflect the amount of work under way.
"Becky" spoke to the BBC on condition of anonymity, and said she has watched nearly three series of comedy The Good Place, despite being available to help isolate people.
"I'm yet to make a single phone call or be assigned a case," the nurse said.
"I've had no contact from anyone. I've had no contact from supervisors. I've literally been on the system, refreshed the system, and entertained myself during that watching Netflix.
"I've just watched it alongside going back to the system, refreshing it, occasionally having to log back in because it's timed out. I have yet to have contact with anybody regarding contact tracing."
It came as Channel 4 News reported data showing 4,456 confirmed Covid-19 cases were reported to the Test and Trace scheme between 28 May, when it launched, and 31 May.
The data - described by the government as "outdated" - showed those confirmed cases passed on 4,634 contacts, but Channel 4 reported just 1,749 of these have been contacted by tracers.
Latest daily figures showed 1,613 people tested positive for coronavirus up to 09:00 BST on Tuesday.
Anthony Costello is a professor of global health at University College London who formerly worked at the World Health Organization (WHO).
He told Victoria Derbyshire the Test and Trace system was unlikely to be picking up more than 30% of coronavirus cases and may be missing at least two-thirds of contacts.
"That's why your nurse has not had any calls. It is not fit for purpose yet. The worrying thing is can it ever be fit for purpose? Why was it set up like this? You need speed and you need trust," he said.
He added that the system should instead revolve around local GPs and that the current system risked giving people a false sense of security.
Speaking at Prime Minister's Questions on Wednesday, Boris Johnson pledged a new 24-hour target for test results, except for tests delivered by post.
The pledge followed comments by former health secretary Jeremy Hunt who said the quick turnaround of test results was crucial for the Test and Trace scheme to be effective.
The NHS Test and Trace scheme in England is intended to map a person's networks and close contacts once they have received a positive coronavirus diagnosis.
It is being run in part by the private outsourcing company Serco and is led by the chair of NHS Improvement and former TalkTalk chief executive Baroness Dido Harding.
One NHS job advert for a clinical contact tracer stated the role paid up to £27.15 per hour and described suitable applicants as nurses, dentists or vets, among others.
Other non-clinical and administrative roles on the scheme are reportedly paid less than £10 per hour.
'Not ready yet'
Becky - who said nursing was a vocation - described her experience with Test and Trace as "frustrating".
"I think it's appalling, I think it's dishonest," she said.
"We're trying to build a very large system that's trying to keep people in England safe and try and prevent a second spike.
"I understand it's complex and I understand there's going to be challenges."
"It's not ready yet. Hold fire. The released aspects of lockdown - which without track and trace - are not safe to do so," Becky added.
"Not having a system up and running is obviously frustrating but it's about people's lives."
A Department of Health and Social Care spokesperson said: "The new NHS Test and Trace service is up and running and will help save lives. These claims do not reflect the huge amount of work already under way.
"Anyone in this country can book a test and we have over 25,000 contact tracers in place to undertake this vital work.
"All staff have been trained and are fully supported in their work following procedures designed by public health experts."
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