The Government has announced workers in certain sectors can now be exempted from self-isolation rules as supply chains slow down and supermarkets experience empty shelves.

How the new rules will work in practice are still being figured out.

Here, the PA news agency takes a look at the main issues.

Who is exempt?

Sixteen sectors are entitled to apply for an exemption. These are energy, civil nuclear, digital infrastructure, food production and supply, waste, water, veterinary medicines, essential chemicals, essential transport, medicines, medical devices, clinical consumable supplies, emergency services, border control, essential defence outputs, and local government.

Can any staff member in those industries ignore a ping from the NHS app?

No. Only around 10,000 food supply chain workers are expected to be entitled to leave self-isolation to carry out essential work, with tens of thousands more in other eligible sectors. They must be fully vaccinated, with their second jab at least two weeks ago. Anyone with a positive Covid-19 test will have to self-isolate and only “close contacts” will be exempt.

How will it work?

There are understood to be two ways in which exemptions can be confirmed, although firms have highlighted some confusion. Around 500 firms in the food supply chain have been contacted directly by the Government to use the scheme, Environment Secretary George Eustice told Sky News on Friday. Other companies who believe they are eligible have been encouraged to apply for an exemption. This involves writing to the Government laying out how many sites they believe cover the exemption and how many staff are currently self-isolating.

When will they get an answer?

It is still not known how quickly the Government will process requests, but it is thought they will not give answers to businesses until Monday.

If they are overwhelmed with requests, it could be even longer.

What is the Government saying?

It said it will assess each application as to “whether they work in critical elements of national infrastructure and whether their absence would be likely to lead to the loss or compromise of this infrastructure”.

In particular, applicants will be accepted only if not working would cause a “major detrimental impact on the availability, integrity or delivery of essential services – including those services whose integrity, if compromised, could result in significant loss of life or casualties, significant impact on national security, national defence, or the functioning of the state.”

Are bosses happy with the new arrangements?

Most have welcomed a shift in the rules but others have been critical over the lack of detail for how quickly it will be enacted.

Food firms have also highlighted a lack of clarity in the application process and stressed the need to resolve this issue with haste.

The retail sector is also concerned that whilst supply chains will be able to continue operating, store staff are not exempt, which could see shops forced to close.

Richard Walker, managing director at Iceland said: “We’re encouraged to hear that supermarket depot workers and food manufacturers will be exempt from Government rules, but deeply disappointed to see supermarket store workers omitted from the list.”