The UK’s Covid alert level increased from level three to level four in response to the soaring case numbers, but prime minister Boris Johnson has so far ruled out any further restrictions.
Here’s everything you need to know.
When do I need to self-isolate?
The self isolation period for people infected with Covid-19 in England has been cut once more, down to five full days.
It was initially reduced from 10 days down to seven, with two lateral flow tests to be taken 24 hours apart on day six and seven of isolation, and if the result comes back negative the quarantine period can end.
But health secretary Sajid Javid has announced that the self-isolation period for people who test positive for Covid is to be reduced to five full days from Monday 17 January.
It means that people will be able to leave isolation if they test negative on a lateral flow kit on days five and six.
The move comes amid pressures on staffing numbers in certain industries, including the NHS, and is based on data from the UK Health Security Agency, which found two-thirds of people are no longer infectious on day five of isolation.
The isolation period is different for those who do not live in England.
Those who are double jabbed and identified as a contact of someone with Covid-19 do not need to self isolate, but instead should take a daily lateral flow test.
This guidance applies to all cases of coronavirus, regardless of whether it is the Omicron variant or other strains.
The government has said all contacts will be contacted by NHS Test and Trace via text message, email or phone.
You can be a contact of someone with Covid-19 any time from two days before that person developed symptoms, or took a positive test, and up to 10 days after.
Contacts will be advised to get a box of seven lateral flow tests free of charge from NHS Test and Trace either through pharmacies, schools or home delivery by ordering online.
As is the case now, anyone whose rapid test comes back positive, or who develops Covid symptoms, should self-isolate and take a PCR test to verify the result.
If the PCR result comes back positive, contacts must self-isolate for 10 days from the day they took the positive rapid test or developed symptoms, and do not need to continue taking rapid tests during that isolation period.
If the PCR result comes back negative, contacts can leave self-isolation but should continue to take rapid tests for the remainder of the seven days.
The DHSC said anyone identified as a contact with a negative lateral flow test is “strongly advised” to limit close contact with other people outside their household, especially in crowded or enclosed spaces and with anyone who is more vulnerable.
How long do I have to self-isolate?
In Scotland, Wales and Northern Ireland, the self-isolation period starts immediately from when your symptoms started, or from when a positive lateral flow or PCR test was taken if you do not have any symptoms - whichever test was taken first.
From this point, your isolation then includes the next seven full days. Release comes if you test negative on days six and seven of isolation and don’t have symptoms. The devolved nations moved to cut the isolation period after England had announced its changes. It remains unclear if Scotland, Wales and Northern Ireland will reduce the self isolation period to five days in line with England.
From Monday (17 January), those in England who receive a negative lateral flow test result on day five and six of their self-isolation period, and are vaccinated, no longer have to quarantine for the full 10 days.
Instead, a lateral flow test must be taken 24 hours apart on day five and six of the isolation period, and if this is negative, quarantine can end.
During the isolation period, you must stay at home and not leave your house to go to work, school, or public areas, or use public transport.
You must not go outside to buy food or other essentials, except in specific limited circumstances.
Exercise must only be taken within your home, garden or private outdoor space.
In some cases, the person you have been in close contact with will be asked by NHS Test and Trace to take a follow up Covid-19 test.
If this result is negative you will be contacted by NHS Test and Trace to let you know you can stop self-isolating.
You can only end self-isolation before 10 full days are complete if you have been contacted by NHS Test and Trace and advised to do so.
Do I need to take a test?
Government guidance states that you should arrange to take a PCR test as soon as possible within your isolation period to allow NHS Test and Trace to identify people you have been in contact with.
You can do this by ordering a home test kit online or booking an appointment at a test site.
It is recommended that test sites are only used if you are unable to use the home PCR testing service.
If your PCR test result is negative, you should still stay at home and self-isolate as you could still become infectious during this period.
If your PCR test result is positive, you should follow the advice for people with Covid-19 to stay at home and start a further full seven day isolation period, regardless of where you are in your original week-long quarantine. This means your total isolation period will be longer than seven days.
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