Supermarkets have said that they may have to close early or shut altogether if the number of self-isolating employees continues to soar.
Marks and Spencer claimed the quantity of workers “pinged” by the Test and Trace app was increasing exponentially and could lead to shorter opening hours.
Another major grocer, which asked not to be named, warned of disruption to food supplies.
It comes after more than 500,000 alerts were sent last week by the app, a weekly rise of 46 per cent.
Marks and Spencer chief executive Steve Rowe told The Times that the numbers forced to self-isolate is “a major issue across every industry”.
“Our Covid cases are roughly doubling every week and the pinging level is about three to one of Covid cases, so we’re seeing that growing exponentially,” he continued.
“If there’s shortages we’ll have to manage it by changing hours of stores, reducing hours.”
From 16 August, people who have been vaccinated twice can take a PCR test instead of self-isolating if they are pinged.
However, a supermarket told the BBC: “The clock is ticking and the government needs to act fast to get people back to work if they have a negative test.
“If not, we could be heading towards crisis point next month.”
The British Retail Consortium (BRC) has called for the government to bring forward the mid-August move to avoid “needless” quarantining.
“We are already seeing a serious impact on retail operations as a result of staff having to self-isolate,” BRC chief executive Helen Dickinson said.
“This will only get worse right across the economy, as cases are already rising fast and the final restrictions are eased.”
Last week, she warned MPs that some shops had lost 20 per cent of their employees.
The news comes as Boris Johnson and Rishi Sunak backtracked on a decision not to self-isolate after coming into contact with health secretary Sajid Javid, who has tested positive for Covid-19.
The pair had initially planned to continue as normal under a pilot scheme.
However, they came under heavy criticism and were accused of running a “get out of jail free” programme.
“Shame the hundreds of Iceland staff who’ve been pinged can’t avoid self-isolation,” Iceland managing director Richard Walker tweeted.