Boris Johnson’s government will stick to its plan to keep self-isolation rules in place until 16 August despite the “pingdemic” crisis caused by staff shortages, a senior minister has said.

       Business secretary Kwasi Kwarteng insisted that people must self-isolate for 10 days when “pinged” by the NHS Covid-19 app for another month – despite pleas from businesses and unions to immediately allow the double-jabbed to avoid quarantine.

       Iceland has revealed it has been forced to close some stores, Greene King has shut 33 pubs, and some London Underground lines have cancelled trains – all because of staff shortages caused by the app.

       “There isn’t any movement on it,” Mr Kwarteng told LBC on Monday. “It’s going to be 16th August. We’ve got to be extra cautious, so that’s why we’re going to be asking people to self-isolate until the 16th of August.”

       Asked if four weeks was a “long time” for businesses to cope with staff shortages, Mr Kwarteng said: “It is, it is. When I speak to business people, people raise this all the time – it’s the single biggest issue.”

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       He added: “But the health experts we’ve talked to have a very clear reason for 16th August and we’re sticking to it. It’s not going to last forever. The restrictions will be lifted entirely on 16 August. What we need to do is stick to the plan we have.”

       The CBI urged the government to immediately allow double-jabbed individuals not to self-isolate for 10 days, rather than wait until 16 August for the rules to change. “Against the backdrop of crippling staff shortages, speed is of the essence,” said CBI president Lord Karan Bilimoria.

       Richard Walker, managing director of Iceland, said the closures of some stores had become necessary because around 1,000 employees were self-isolating. He urged the government to move to a “test and release” model.

       “Staff absences rose by 50 per cent last week and the trend is sharp and quick – not just affecting our own colleagues but those throughout our supply chains and logistics networks,” Mr Walker said.

       Nick Mackenzie, chief executive of pub chain Greene King, told BBC Radio 4’s Today programme that 33 pubs have been shut due to lack of staff. “This is a problem and I think it could get worse. It is disruptive to the business.”

       The Rail, Maritime and Transport union said Saturday’s closure of the Metropolitan line due to key staff being pinged showed how transport services were “on a knife edge”.

       There were delays reported on both the Metropolitan and Central lines on Monday due to more train cancellations after drivers were pinged.

       Asked about meetings he had with businesses chiefs who want the 16 August date brought forward, Mr Kwarteng said: “I said I would make representations in government and see what could be done. But we’ve taken a collective decision. I think this is the right decision.”

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       Earlier on Monday, vaccine minister Nadhim Zahawi suggested there would be no changes to the NHS Covid app’s sensitivity, after calls for it to be dialled down so less alerts were sent out.

       However, it has emerged that frontline NHS staff in England who are double-vaccinated will be allowed to carry on working when pinged in “exceptional circumstances”.

       The Department of Health and Social Care said the exemption would only apply in cases where the absence of staff could lead to a “significant risk of harm”.

       NHS staff in Scotland will shortly receive new guidance on self-isolation if they are a close contact of a coronavirus case, the deputy chief medical officer has said. Dr Dave Caesar said the new advice would come “in the next day or two”.