Daily testing for anyone double-jabbed who comes into contact with a COVID-19 case will start from Tuesday.
Those fully vaccinated should take a daily lateral flow test for seven days to slow the spread of the virus, the government has said.
Unvaccinated adults must continue to self-isolate for 10 days if they are a contact of someone with COVID, and anyone who tests positive or develops symptoms will need to self-isolate.
People will be contacted by NHS Test and Trace or via the NHS COVID-19 app to tell them they are a contact of someone who tested positive and what action they need to take.
The move comes following a significant rise in Omicron infections in the UK with the variant expected to become the dominant strain in the UK by mid-December.
Health Secretary Sajid Javid said: “We are taking this proportionate and more practical measure to limit the impact on people’s day to day lives while helping to reduce the spread of Omicron.
“Vaccines remain our best defence and I urge anyone yet to get a first and second jab to come forward and those eligible for a booster to get boosted as soon as possible.”
The Department of Health and Social Care (DHSC) added the daily testing is aiming to replace the requirement for Omicron contacts to isolate for 10 days.
The plans also aims to protect the public by identifying asymptomatic cases and stopping chains of transmission.
The DHSC said testing daily with lateral flow tests will then help with understanding how and where the virus is spreading.
The department went on to add that close contacts of people who test positive are at higher risk of getting COVID and daily testing will therefore help ensure people are not passing the virus on to others without realising.