London Mayor Sadiq Khan wrote to UK Prime Minister Boris Johnson on Friday asking for a change in Covid-19 rules so those who are fully vaccinated can avoid self-isolation by taking a PCR test. His plea came with businesses across the British capital struggling to contend with debilitating staff shortages as a consequence of the<a href="https://www.thenationalnews.com/world/uk-news/2021/07/21/british-prime-minister-defends-covid-pingdemic/"> </a><a href="https://www.thenationalnews.com/world/uk-news/2021/07/21/british-prime-minister-defends-covid-pingdemic/" target="_blank">so-called “pingdemic"</a>. Last week, a record 618,903 people in England and Wales were instructed to self-isolate by the UK's National Health Service Covid-19 app. The spate of pings is being sparked by increasing case numbers in the UK, with daily infections for more than a week now consistently topping 40,000. <br/> Writing on behalf of the London Covid Business Forum, Mr Khan cited “the continuing mixed messages from ministers around self-isolation” and the harmful effect it was having on the capital's businesses. “Many hospitality businesses, such as pubs and restaurants, are already struggling with staff shortages,” he wrote. “These shortages have been exacerbated, in some cases leading to temporary closure, by large numbers of employees being simultaneously advised to isolate by the NHS Covid app.” He expressed concerns that closures in the “crucial summer months” would jeopardise the long-term prospects of these businesses before outlining his proposed solution. “We are therefore calling on you to ensure that the necessary testing is in place to enable people who have been double vaccinated for longer than two weeks and pinged by the NHS Covid app to immediately return to work, following a negative PCR test, rather than having to self-isolate. “It is vital that both employers and employees retain faith in the NHS Covid app to help prevent the spread of the virus and further damage to London’s economy, and that is why we hope you will give urgent consideration to our request.” Mr Khan is not a lone voice in opposition to current protocols around self-isolating following an alert, with some going further and suggesting the app should be scrapped altogether. “People working in the NHS have been told to delete it … I don't think the app saying someone might have passed [you] by in a supermarket is actually that useful any more,” Prof Tim Spector, an epidemiologist at King's College, London, told<i> Sky News</i>. “Employers have got to use common sense in this. It seems to be overkill.” Mr Johnson, <a href="https://www.thenationalnews.com/coronavirus/2021/07/17/all-adults-in-uk-offered-covid-19-vaccine-ahead-of-freedom-day/" target="_blank">himself currently isolating</a>, has urged the public to continue to self-isolate if pinged but confirmed that from August 16, the system would change to contact testing and not contact isolation.