ITV News Health Editor Emily Morgan has more on the latest changes
The coronavirus self-isolation period has been reduced from 14 to 10 days for domestic Covid-19 contacts and for those returning from countries not on the travel corridor list.
The change, which applies in all UK nations, will come into effect from 00:01 on Monday December 14.
The 10 day self-isolation countdown begins "on the day after exposure, a test or the start of symptoms".
Those who have been in isolation since before Monday will also be allowed to cut their isolation time to 10 days.
It means if someone was on their 12th day on Monday, they could end their period of self-isolation.
The new rule was announced in a joint statement from all four UK chief medical officers, who said they are "confident" after "reviewing the evidence" that they can reduce the period of self-isolation.
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But they cautioned that "self-isolation is essential to reducing the spread of Covid as it breaks the chains of transmission".
“People who test positive should continue to self-isolate for 10 days from onset of symptoms or 10 days from point of taking a positive test if asymptomatic. We urge everyone to self-isolate when appropriate, it will save lives," the statement added.
Due to issues around technology, advice from the NHS Covid-19 app will only update from Thursday December 17.
If someone is contacted by both the app and the NHS Test and Trace, they should follow the advice of the contact tracers.
But if they are advised to isolate by the app and not a contact tracer, then they can leave quarantine when the isolation countdown says three days.
If someone is alerted by the app before December 17 that they must isolate, they can end their quarantine period when the countdown timer says three days.
The news will be a small boost for travellers returning from the Canary Islands, which was removed from the travel corridor list on Thursday evening.
The changes come into force from 4am on Saturday morning, meaning anyone returning to the UK after that day must isolate for 10 days instead of 14.
There are hopes that vaccine roll-out could soon remove the need for restrictions such as social distancing and self-isolation, however it is not thought vaccines will have an impact on virus transmission until spring.
England’s deputy chief medical officer Dr Jenny Harries said reducing the self-isolation period to 10 days was a “reasonable balance between managing the risk to the public but allowing us not to intrude on their lives”.
“The science is based on a continuous accumulation of evidence through the pandemic,” she told reporters.
“So Sage, the Scientific Advisory Group for Emergencies, has looked at this, as well as a number of academic institutions, the Nervtag, the specialist respiratory virus group.
“And all of those combined together showed that the tail-end of infectiousness, if you like, is the one where an individual is least likely to transmit infection.
“So allowing somebody out of self-isolation a short time earlier than that is a reasonable balance between managing the risk to the public but allowing us not to intrude on their lives.”