LONDON — Britain's government has amended self-isolation rules for workers in key sectors who have come into contact with a person who has COVID-19 after staff shortages disrupted the national food supply.

The measure applies to 16 sectors including energy, civil nuclear, food production and supply, waste, water, veterinary medicines, essential chemicals, essential transport, medicines, medical devices, clinical consumable supplies, emergency services, border control, essential defense outputs and local government.

Employers in these sectors can name a limited number of fully vaccinated workers whose absence could cause serious disruptions. These workers will then be able to continue working even if they are alerted by the National Health Service's Test and Trace app that they have come into contact with a person who tested positive for COVID-19.

They will, however, have to submit to daily testing for a week and self-isolate if found positive.

About 10,000 staff across more than 400 sites in the food supply chain alone should fall under the scheme, Environment Secretary George Eustice told Sky News.

"We're talking principally here the supermarket depots, the distribution centers where all of the work happens to get food out to those supermarkets. It doesn't include stores themselves because that would be a big departure from the approach we have now but certainly, this is going to do a very long way to get the food supply chain working properly," he said.

The government said the scheme is only intended to run until August 16 when fully vaccinated close contacts will be exempt from self-isolation.

It comes after what has been dubbed a "pingdemic" forced more than 600,000 people to self-isolate in the week to July 14 because they had come into contact with a person testing positive. This led to some supermarkets' shelves remaining empty and forcing some to close multiple stores.

Industry experts had urged the government to amend its policy warning of consequences on the economy.

Hannah Essex, co-executive director of the British Chamber of Commerce, said the government's latest announcement "will be a relief to some businesses" but that it will "leave many more still facing critical shortages and lost revenue as the number of people being asked to isolate remains high."

"Nearly half of the businesses we surveyed this week have had staff either off sick with COVID or self-isolating in the past two weeks.

"Pilot schemes for 'test to release' options have been running for some time now and we would urge the government to immediately bring forward the results of those test schemes and set out how this could be used to enable more double vaccinated people to avoid self-isolation beyond this narrow group of critical workers," she added.

More than 30,000 infections have been recorded daily across the UK since July 7 with a peak of more than 51,000 observed on July 15.

The surge in cases has been blamed on the Delta variant which UK authorities say now accounts for 99 percent of new infections in the country.

More than 87 percent of Britain's adult population has so far received at least one dose of the vaccine and 69.2 percent is fully vaccinated.