The boss of Marks and Spencer has warned that store hours may have to be cut amid Covid 'pingdemic' chaos in the wake of 'Freedom Day' next week.
Steve Rowe said the number of test and trace app 'pings' is growing exponentially - at about three times the rate of Coivd cases - and that by mid-August as many as one in five supermarket workers could be in home isolation.
'If there's shortages we'll have to manage it by changing hours of stores [and] reducing hours,' he said.
His warning comes amid fears of food shortages when supply chain workers such as lorry drivers inevitably caught in the track and trace net, meaning supplies rot before they can be sold.
Tesco told ministers last month that 48 tons of food was being binned every week due to a driver shortage, a situation that is bound to be made worse when almost all Covid restrictions are lifted on Monday.
The NHS test and trace app has been in use since last year, sending alerts to 'close contacts' of Covid cases and telling them to self-isolate to reduce the risk of asymptomatic infection.
But, until the development of vaccines, high case numbers meant lockdowns - reducing the number of contacts each person had and therefore the chances of them getting 'pinged'.
Now, with vaccines keeping hospital admissions down, the government is content to let cases rise significantly while allowing people to resume near-normal daily activities with lots of social contact - a combination that will massively increase the number of 'pings' the app sends out.
Chief executive of Marks & Spencer Steve Rowe said the swathes of staff being forced to self-isolate meant shops will have to reduce opening hours
Up to 1million people were asked to self-isolate last week, data suggests. But that figure could hit 5.6million by the end of the month, if cases spiral by 75 per cent every week (right), according to MailOnline analysis. Separate projections based on a growth rate of 40 per cent - similar to what Test and Trace reported last week - still says the number of people self-isolating could hit 3million a week. But the true figure will be much lower because many people who are told to self-isolate end up testing positive, and some people will be flagged down by both NHS Test and Trace and the app
Around 1.8million people were asked to self-isolate last week in England, data suggests. That includes 194,000 people who tested positive, 520,000 who were 'pinged' by the app, almost 340,000 who were contacted directly by Test and Trace, and 750,000 schoolchildren
The number of alerts sent out in relation to venues also more than doubled in seven days
MailOnline has looked into the legal guidance behind whether someone has to self-isolate if they are Covid positive, or told to by the app or Test and Trace.
Do I have to self-isolate if I get 'pinged' by the app?
App users who are 'pinged' after coming into contact with someone who has tested positive are not obliged to stay at home.
They are kept anonymous through the app, meaning authorities are unable to track them down if they have been told to quarantine.
Professor Lilian Edwards, a top lawyer who advised the Government on the app, said today people do not have to follow notifications from the software.
'I think what's getting lost in the traffic here is that you are not breaking the law if you do not self-isolate having been pinged by the app,' she told the BBC's World at One.
The Health Protection (Coronavirus, Restrictions) (Self-Isolation) (England) Regulations 2020 says people alerted by the app do not have to self-isolate (bolded in red)
'You are only breaking the law if you are rung up by a manual contact tracer.
'Therefore, there is room there for discretion both from managers in the workplace and from workers as to whether they think they are a risk.'
However, the instruction becomes legally enforceable as soon as someone who is pinged attempts to apply for the Government's isolation support payments.
Do I have to self-isolate if test and trace contacts me?
People contacted by NHS Test and Trace workers do have to self-isolate under regulations brought in last autumn to tackle coronavirus or face hefty fines.
That rule won't be dropped for fully vaccinated adults until August 16.
Britons who are contacted by test and trace must self-isolate at home for ten days. They must isolate for ten days regardless of whether they have symptoms or get a negative test.
People they live with will also be required to self-isolate for ten days.
Do I have to self-isolate if I test positive?
People who have received a positive test must isolate for ten days after displaying symptoms or their test date if they do not have symptoms, while members of their household must isolate for 14 days
Britons found breaking these rules could face a fine of £1,000 for the first offence.
This rises to £10,000 for people who repeatedly refuse to self-isolate after testing positive.
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Staff shortages at ports and in the meat industry mean supermarket shelves could be left empty, with supply chains badly affected
And Jeremy Hunt, the former Health Secretary, today claimed the app needs to be changed, adding that a quarter of junior doctors are currently in isolation.
Ministers have said the lifting of restrictions on Monday is likely to push daily infections to more than 100,000, which could force around half a million a day to self-isolate.
Analysis by MailOnline suggests that in a worst-case scenario around six million adults could be in isolation by the end of the month.
Britain's daily infection toll breached 50,000 yesterday for the first time since January. Anyone who tests positive is told to self-isolate and has their contacts traced.
But because the Bluetooth phone app 'pings' all those who have been in close contact with positive cases, the number of people self-isolating at home at any one time is far higher.
Unlike those people contacted by phone, it is not a legal requirement to self-isolate after being pinged by the app. But Downing Street today made it clear it expects people to do so.
It raises the prospect of the economy grinding to a halt due to a chronic lack of available workers, even after the lockdown is supposed to have ended .
Business leaders and trade unionists from across all sector of the economy lined up to warn the Government that a major rethink is needed, because the current situation is not sustainable.
A fifth of all private sector workers are currently having to self-isolate, according to industrial analysis.
Chief executive of the UK Major Ports Group Tim Morris said the 'pingdemic' is the most 'significant threat to ports' resilience we have seen yet'.
He suggested people being forced to stay at home could lead to food supply chains being at risk.
Mr Morris told the Daily Telegraph: 'If the current trajectory of absences continues without the Government taking any action, there has to be a risk of disruption to important supply chains, including food.'
Meanwhile, meat workers are in talks with
