People who test positive for coronavirus or show symptoms in the UK must now self-isolate for at least 10 days, rather than seven.
The change, announced by the UK’s chief medical officers, comes as ministers try to avoid a resurgence of the virus.
Until now, those showing key symptoms – a new continuous cough, a temperature or loss of taste or smell – have had to self-isolate for at least a week.
The new advice is in line with World Health Organization guidance.
The chief medical officers said the change 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”.
Evidence shows that people with Covid-19 have “a low but real possibility of infectiousness” between seven and nine days after falling ill, they said.
People are most contagious just before they first display symptoms and for the first few days afterwards. But scientists say evidence that they could pass it on up to nine days later has “strengthened”.
It comes after the prime minister warned of signs of a “second wave” of the pandemic in parts of Europe.
Speaking on BBC Breakfast before the announcement, Health Secretary Matt Hancock said the government wanted to “take a precautionary approach” and “protect people from that wave reaching our shores”.
Meanwhile, the government is also expected on Thursday to review the restrictions in Leicester again, a month after the city was put into extended lockdown following a spike in cases.
Two or three weeks ago the message from the prime minister was that, hopefully, we would be back to near-normality by Christmas.
The direction of travel was one of lockdown easing, with pubs and restaurants reopening, as well as a feeling that we seemed to be getting through it.
Now, there’s a real sense of the brakes beginning to go on.
We saw it with the quick quarantine measures imposed on people returning from Spain. Luxembourg may well have similar restrictions soon and they’re keeping an eye on Belgium too.
We had restrictions imposed in Oldham to curb the virus there and now there’s been an extension of the self-isolation period. Read more