LONDON — Employers in Britain are raising fears that a "pingdemic" could cause a major economic disruption this summer, after more than half a million people in a single week were pinged by the government's contact-tracing app, alerting them they may have been exposed to the coronavirus and should stay home for up to 10 days.

Already, factories, pubs, restaurants and schools are reporting staff shortages resulting from quarantine guidance, which in England and Wales, for at least another month, still applies to people who are fully vaccinated.

New figures published this week show the National Health Service covid-19 app sent more than 520,000 exposure notifications between July 1 and July 7 — up 46 percent from the previous week and a record high. The app, which has been downloaded more than 26 million times, was not in as widespread use during previous waves of the virus in Britain. But the numbers still reflect a high level of community spread. On Friday, the United Kingdom reported 51,870 new coronavirus cases, the highest daily figure in six months.

Health policy experts expect those numbers to rise exponentially, because of the highly contagious delta variant, because England’s hosting of Euro 2020 saw thousands of people congregating to cheer on the national soccer team, and because England is about to lift the last of the major pandemic restrictions on Monday.

Britain’s health secretary said the coronavirus case number could top 100,000 a day this summer.

At a Nissan factory in northern England, the largest car factory in the country, up to 900 employees — 15 percent of the workforce — are quarantining after exposure or isolating after a positive test, according to the BBC. Rolls-Royce has said it won’t rule out having to shut down production.

In the hospitality sector, which was already struggling with vacancies, 1 in 5 workers are reportedly quarantining or isolating. There were scenes of chaos this week at Heathrow Airport, as long queues of passengers overwhelmed the sparser-than-usual security staff.

The Guardian newspaper reported that garbage collections have been disrupted because of staff shortages in several English cities “amid a warning that services are unsustainable due to rising infections and a high ‘ping’ rate.”

In schools in England, which are still in session, more than 800,000 students — or 1 in 9 — were out last week for virus-related reasons.

Anxiety about getting “the ping” goes beyond employers and their workers. The government’s Office for National Statistics, which does surveys to measure behaviors like prevalence of mask-wearing, asked Britons what they most looked forward to after restrictions are lifted on Monday. More than half (54 percent) said going on vacation abroad — holidays that could be dashed if they were instructed to stay at home.

Britain’s health secretary, Sajid Javid, announced Saturday that he had tested positive for the coronavirus. In a video posted on Twitter, Javid said he was self-isolating at home to await further test results. He described his symptoms as “very mild.”

Speaking to the BBC on Friday, Lucy Frazer, the solicitor general, emphasized that quarantining after possible exposure was “an important tool” in helping to tackle the virus. She added that the government was aware of the “significant” impact it was having on businesses and was conducting pilot studies of alternative solutions. The app is only advisory, but Frazer said she “hoped people would follow the obviously appropriate guidance, which is if you are pinged you stay at home and isolate.”

Studies from previous periods of the pandemic showed a low rate of adherence to NHS quarantine guidance. And that guidance is about to change once again. Starting Aug. 16, fully vaccinated people won’t need to stay home after exposure but will be encouraged to take a test.

A new Savanta ComRes poll found that a third of people who have downloaded the NHS covid app plan to delete it after restrictions are lifted this coming week.

“I deleted the app this morning but after Monday I will still wear my mask on busses and in supermarkets,” wrote one user on social media, responding to a query on the topic.

Still, enough people are following the current guidance that it is having an impact on workplaces. And employers say a month is a long time to wait for less rigid guidelines.

According to an analysis by the Guardian, as the number of cases continues to rise, up to 10 million people could be urged to quarantine within a six-week period.

Writing in the Daily Mail, Richard Walker, managing director of Iceland Foods, a giant supermarket chain, said: “I find myself looking towards next Monday’s so-called ‘Freedom Day’ from Covid restrictions not with relief and enthusiasm, but with a sense of dread.”

He said people who are exposed should be given a test to determine if they can return to work.

“This simple change from Test and Trace to ‘Test to Release’ would turn a ten-day absence into one or two days, and provide huge relief to employers, employees and customers,” he wrote.

Scientists are mixed on the continued importance of quarantining for those who are fully vaccinated.

Stephen Griffin, who heads a virus research group at the University of Leeds, said he’d support more restrictions — for quarantining and for social distancing more broadly — at a time when only half the population is fully vaccinated.

“If you wanted to design an experiment to generate a really nasty variant, you’d have high prevalence in a partially vaccinated population, and that’s exactly where we are about to be,” he said.

Paul Hunter, a professor of medicine at the University of East Anglia, said that while it was a “difficult decision,” on balance, once the government lifts restrictions on Monday, people who are fully vaccinated shouldn’t have to quarantine unless they develop symptoms.

“We have to come out of this at some time,” he said, suggesting summer is a good moment to open society further, as “schools are out and there aren’t as many other virus around.”

He added that because so many people have completed their vaccinations recently, their protection should be strong.

Hugh Osmond, the founder of Various Eateries, a restaurant and bar group with 11 sites, told The Washington Post that exposure notifications were creating chaos in the workforce. He said he was planning to open a new venue in Bristol on Monday, but had to postpone those plans after 16 of his staff at that restaurant got pinged.

“It’s impossible to try and run the business with that kind of unpredictability,” he said. “It’s not just our industry. It’s happening in the NHS, public transport, food manufacturing, delivery drivers. We cannot get to normal or normal-ish if half a million people are off work.”

William Booth contributed to this report.