Two cases of the Omicron variant feared to have higher re-infection rates have been detected in the UK.
The individuals and all members of their households were told to enter self-isolation after one case was detected in Chelmsford, Essex, and another in Nottingham.
The UK Health Security Agency confirmed the cases, which are both believed to be connected and linked to travel to southern Africa, after genomic sequencing overnight.
British Health Secretary Sajid Javid has ordered targeted testing in the affected areas and said Boris Johnson will “set out further measures” during a Downing Street press conference later on Saturday.
“We were concerned from the moment we first identified this new variant,” Mr Javid told reporters.
“It’s a deeply concerning new variant and we do need to learn more about it but the fact that we now have these two cases in the United Kingdom does mean we need to take further measures and that’s why I’ve set this out today.”
Mr Javid did not say whether further restrictions could be added ahead of Christmas in light of the new strain, which the World Health Organisation (WHO) has designated a “variant of concern”.
Instead, he said: “We’ve made a lot of progress, we all want to see that protected and if anyone’s sitting at home thinking what can I do? Get vaccinated.”
It comes as the number of Covid-19 patients in hospital falls sharply in Ireland.
Today there has been a decrease of 35, with a total of 536 people currently receiving hospital treatment.
A further 4,791 cases were also recorded today by officials at the Department of Health while the number of people being treated in ICU remains at 118.
New restrictions are being imposed on travel from countries in southern Africa as the world scrambles to contain a new variant of coronavirus that has the potential to be more resistant to the protection offered by vaccines.
A host of countries, including Australia, Brazil, Canada Iran, Japan, Thailand and the US, joined others, including the European Union and the UK, in imposing restrictions on southern African countries in response to warnings over the transmissibility of the new Omicron variant — against the advice of the World Health Organisation.
The British government has added four extra African nations to the travel red list.
Mr Javid said anyone who has travelled in the last 10 days to the 10 countries now on the red list, with Malawi, Mozambique, Zambia and Angola being added to South Africa, Botswana, Lesotho, Eswatini, Zimbabwe and Namibia, they must self-isolate and take PCR tests.
England’s chief medical officer Professor Chris Whitty said: “We will continue to work closely with the international community to quickly gather and analyse information on this variant to understand any possible increase in transmissibility or resistance to vaccines.”
The UK is the second European nation to have reported the presence of Omicron after Belgium said it had identified a single case on Friday.
Ministers said non-UK and Irish residents who have been in Malawi, Mozambique, Zambia and Angola in the previous 10 days will be refused entry into England from 4am on Sunday.
Those who are permitted to return will be ordered to isolate in a Government-approved facility for 10 days.
South Africa, Botswana, Eswatini, Lesotho, Namibia and Zimbabwe were added to the red list on Friday, and the UK imposed a ban on flights leaving from those nations.