Some critical workers will be exempt from isolating if they come into close contact with a person who has Covid-19, the Government has announced.

The purpose of the new measures is to keep critical supply chains of items like food and critical services like power and water running.

Businesses will self-assess whether they can join the scheme, with close contacts able to continue working provided they return a negative rapid antigen test. Close contacts who work alone can continue to operate in a bubble of one.

Critical services include food production and its supply chain, health and emergency services, lifeline utilities such as power and water supplies, transport, critical financial services, news media, social welfare, human and animal health and welfare.

Covid-19 Response Minister Chris Hipkins said this scheme will help prevent supply chain issues seen in other countries.

"We’ve seen overseas that a combination of high rates of Omicron alongside isolation periods for contacts has put severe strain on supply chains and the provision of important services.”

The rapid antigen tests will be supplied by either the business or service, or through the public health system.

From today (February 10), businesses and organisations can register online as a critical service if they think they meet the criteria for when the country enters Phase 2 of the Omicron outbreak.

Associate Minister of Health Dr Ayesha Verrall said the decision to join the scheme is up to the business, and to keep in mind that rapid antigen tests are about 80 per cent accurate.

“There needs to be an awareness that bringing close contacts into the workplace will come with risks.”

Workers involved in the scheme must be vaccinated against Covid-19 and if they return a positive test, they will need to take a PCR test and isolate.

“Workers will also be expected to remain in isolation outside of work hours as they will in many instances be living with household members who have Omicron,” Verrall said.

Hipkins said the Government is taking a pragmatic approach to Omicron and its management.

"These changes strike a balance between continuing to keep people safe, but also keep businesses and services operating as smoothly as possible."