Businesses in England have complained that too many staff members are being forced to stay at home after receiving self-isolation alerts.
New figures showed the National Health Service test and trace app sent alerts – or pings – to 530,126 people during the seven days to July 7.
It was a 46 per cent increase on the previous week and the highest since data was published in January.
The number is more than 10 times that of the seven days to June 2.
In the final week of April, when indoor dining was still banned, 39,875 close contacts were identified.
Some scientists said the app was sending out so many alerts because of a surge in Covid-19 cases due to increased social mixing after England emerged from lockdown.
They say the app is doing exactly as intended by removing potentially infectious people from the community.
Lucy Frazer, solicitor general for England and Wales, on Friday urged people to isolate if they receive an alert despite acknowledging the system was "frustrating".
"I would hope people would follow the obviously appropriate guidance which is after you are pinged you stay home and isolate," she told the BBC's Radio 4 Today programme.
"We are in the middle of a pandemic and we know the virus spreads without showing any symptoms and the app is one of a number of ways which we’re trying to tackle the virus."
But many have complained the app could be too sensitive, with reports that people have been forced to isolate for 10 days despite never having face-to-face contact with a Covid-19 case.
This could be because the Bluetooth signals relied upon by the app are able to penetrate walls, The Telegraph reported.
The Royal College of Anaesthetists and the Faculty of Intensive Care Medicine called for double-vaccinated NHS staff to be exempt from self-isolation if they are close contacts of Covid cases.
“The risk of patients contracting Covid from vaccinated healthcare staff is minimal compared to the damage that patients could suffer by having their treatment delayed,” it said.
“Without this exemption in place, the NHS will not be able to address the waiting lists. We encourage the Government to not wait until August to free vaccinated healthcare workers from the isolation rules – we need this to happen now.”
Chris Hopson from NHS Providers said hospital trusts were concerned of dealing with a backlog of patients "with large numbers of staff unable to work”.
“We know that national leaders are working hard to find a solution to this problem. The key is that this solution is delivered as a matter of urgency,” he said.
'Critical point'
Businesses are warning of a “pingdemic” with so many people forced to stay at home and unable to work.
One in five workers in hospitality and retail are self-isolating, industry group UK Hospitality said, while some NHS hospitals reported staff absences of 25 per cent.
Bus and train services have been cancelled due to a shortage of drivers.
Engineering company and car manufacturer Rolls-Royce said it may be forced to halve production due to the number of workers self-isolating.
"We are approaching a critical point – it will be necessary to reduce our two shifts to one if numbers of self-isolations continue to rise, effectively halving production,” the company said.
"This would be deeply detrimental to our customers' expectations and our business."
Nissan's UK plant is affected by the same issue with more than 700 workers at its site in northern England reportedly self-isolating.
Meat processors are seeing up to one in 10 of their workforce told to self-isolate.
British Meat Processors Association chief executive Nick Allen said some companies could be forced “to start shutting down production lines altogether”.
“It’s almost on a daily basis we’re getting more reports from members saying they’re having problems,” he said.
“It’s quite a critical point.”
He said some companies were already cutting down on production.
“The objective is to keep food on shelves,” he said.
Hugh Osmon from Various Eateries said, “living with the virus cannot mean we can have half a million people taken out of the workforce”.
“It is absolute chaos and clearly the app isn’t fit for purpose because people are getting pinged all over the place and the vast majority do not test positive let alone get ill,” he said.
“We do believe where people test negative … then of course they should be allowed to go back to work.”
On Monday, Heathrow Airport blamed hours worth of delays on security workers forced to self-isolate after receiving an alert on the app.
Communities Secretary Robert Jenrick said the government was concerned about the number of people being forced off work by the app.
“We are concerned about absences as a result of being pinged, for example. That is one of the reasons why we do need to move to a more proportionate approach,” he told LBC Radio.
“The government is going to be setting out its plans in the coming weeks.”
