Nearly 200 additional people were invited to self-isolate by Test and Trace in Windsor and Maidenhead last week, according to the numbers.

Data from the Ministry of Health and Social Affairs shows 747 people have been asked to self-isolate after coming into contact with someone who tested positive for Covid-19 in the week to July 14 – the latest data available .

That was up from 554 the week before, and it means 1,301 people have been asked to self-isolate in the past 14 days alone.

Contact tracers ask new patients to give details of anyone they have been in close contact with within 48 hours before the onset of their symptoms.

Figures show 832 people who came in close contact with someone who tested positive for Covid-19 in Windsor and Maidenhead transferred to Test and Trace in the week leading up to July 14.

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This means that 85 contacts were not reached by the service. Figures do not include people who have been asked to isolate in specific settings such as schools and prisons.

Across England, more than 223,000 cases were transferred to the contact tracing system between July 8 and July 14, with 475,500 people identified as being in close contact with someone who tested positive.

The number of close contacts recorded is now the highest observed since the week ending January 20.

Separate figures also show that 618,903 alerts were sent to users of the NHS Covid-19 app in England and Wales telling them to self-isolate.

Isolation is recommended, but not mandatory, if someone is alerted by the app, while those contacted by Test and Trace have a legal obligation to self-isolate.

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The government has come under fire after companies revealed they were struggling to cope with the growing number of people being “pinged” by the app.

Images of empty supermarket shelves have been shared widely online, suggesting the app is disrupting the industry.

Richard Walker, managing director of supermarket giant Iceland, said the company needed to hire 2,000 temporary workers to prepare for “the pinging increase”.

The British Retail Consortium urged ministers to ‘act quickly’ to allow fully vaccinated workers, or those who test negative, to be exempted from isolation if notified by the Covid-19 app.

The government will introduce broader easing for all double-bitten people, but that won’t come until August 16 – a month after most coronavirus laws end.

The date “seems far away,” said BRC chief executive Helen Dickinson, however, as she warned stores were closing, hours were reduced and consumers faced fewer choices.

Business Minister Kwasi Kwarteng had to tell businesses to ‘play by the rules’ after a food distribution company struggling with staff shortages advised workers who are nuts about the NHS app to take tests and continue to work, in violation of government advice.

He said: “I would stick to the rules, which are very clear, which say if you are nuts you have to isolate yourself.”

The government was to publish a list of sectors exempted from isolation on Thursday, July 22.