People with coronavirus symptoms now have to self isolate for 10 days, instead of seven.
The government have extended the length of time people with the main symptoms of coronavirus should cease contact with others, in the hopes of preventing a second wave of Covid-19.
The news was announced on Thursday morning by the UK's four chief medical officers.
In a statement, they said that the new advice was based on fresh evidence suggesting that people with mild to moderate symptoms may be infected for longer than they initially thought.
They said: "Evidence, although still limited, has strengthened and shows that people with Covid-19 who are mildly ill and are recovering have a low but real possibility of infectiousness between seven and nine days after illness onset.
"We have considered how best to target interventions to reduce risk to the general population and consider that at this point in the epidemic, with widespread and rapid testing available and considering the relaxation of other measures, it is now the correct balance of risk to extend the self-isolation period from seven to 10 days for those in the community who have symptoms or a positive test result."
Adding: "This will help provide additional protection to others in the community. This is particularly important to protect those who have been shielding and in advance of the autumn and winter when we may see increased community transmission."
Recent findings have showed that people were most infectious before symptoms begun to show, and during the first few days of the infection.
But they have also proved that people could still be infectious up to nine days after catching the virus - even if they felt significantly better.
The new advice is echoed by the World Health Organisation.
It comes as the Prime Minister recently warned a 'second wave' could be as close as two weeks away, based on the trajectories of other countries in Europe.
Speaking on BBC Breakfast ahead of today's new measures, Health Secretary Matt Hancock said the government was keen to "take a precautionary approach" in order to "protect people from that wave reaching our shores"
In case you need a reminder, the NHS state the primary coronavirus symptoms to look out for are:
A High Temperature - this means you feel hot to touch on your chest or back (you do not need to measure your temperature)
A New, Contagious Cough - this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours (if you usually have a cough, it may be worse than usual)
A Loss Or Change To Your Sense Of Smell Or Taste - this means you've noticed you cannot smell or taste anything, or things smell or taste different to normal.
If you think these apply to you, self isolate as instructed, and order a test online here.