The British government is rolling out daily Covid testing to allow workers in critical services in England to avoid self-isolation, amid concerns that mass staff shortages are threatening crucial supplies.

People who are deemed critical workers in key sectors including the food supply chain will no longer need to self-isolate for as much as 10 days if they come into contact with a positive case.

Businesses from stores to car factories have reported growing disruption after hundreds of thousands of people were contacted — or “pinged” — by the National Health Service coronavirus app and told to isolate.

Latest figures from the NHS showed 608,000 people were notified last week, up from 356,000 two weeks before.

Images published in British media showed empty supermarket shelves on Thursday, leading ministers to express concern over potential shortages of goods. The government appealed to the public not to panic buy food.

Environment Secretary George Eustice said he had received assurances from supermarket leaders that the problems were not widespread.

“The last 18 months have demonstrated that we have a highly resilient food supply chain,” he said in an emailed statement. “There are sufficient food supplies in the system and people can and should shop as normal.”

Under new government guidance published Thursday evening, named workers in “specifically approved workplaces” who are fully vaccinated will be allowed to continue working after being identified as a close contact of someone with COVID-19.

Their employers need to apply to the government and demonstrate that the person works in “critical elements of national infrastructure” and their absence would have a “major detrimental impact on the availability, integrity or delivery of essential services” or an impact on national security or defense.

Potential sectors covered by the new program include food production and supply, energy, waste, water, medicines, emergency services, border control and local government.

The process is only intended to run until August 16, when fully-vaccinated people who have been in close contact with COVID-19 cases will be exempt from self-isolation.