Staff in ‘critical sectors’ – including food and water supply, medicines and public transport – will still be able to go to work if their employer gets permission from the government. However, they will be expected to self-isolate when not at work.

Those included in the scheme will need to be fully vaccinated, do a test for Covid-19 each day and can only work if they have a negative test. If they receive a positive result they must stay at home.

The news comes after more than 600,000 people were told to self-isolate in the week up to 14 July. Many will not be paid while they are self-isolating, or will need to cancel holidays.

The critical sectors include 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.

This policy only applies if your employer has received a letter from a government department on which your name is listed – it’s not a blanket exemption for all workers in a sector. In the event of being pinged, a worker will be able to leave self-isolation to undertake critical work but need to quarantine at all other times.

The government says the process will not cover all or, in most cases, even the majority of workers in critical sectors. For example, an exception may be suitable in the case of absences in critical railway signalling roles essential for the functioning of parts of the network but is less likely to be suitable for individual train drivers.

Some workers in the food supply chain industry are included on the list – but not supermarket workers or postal staff, despite food shortages and delays to mail being delivered.

Updated guidance from the government says: “In the small number of situations where the self-isolation of close contacts would result in serious disruption to critical services, a limited number of named workers may be able to leave self-isolation under specific controls for the purpose of undertaking critical work only.”

This process is only intended to run until 16 August 2021, when fully vaccinated close contacts will be exempt from self-isolation.

Separate arrangements are in place for frontline health and care staff.