Boris Johnson will hold a Downing Street coronavirus press conference this evening.

It comes amid concerns about a new Brazilian variant of the virus detected in the UK.

Mr Johnson will be joined by England’s chief medical officer Professor Chris Whitty and chief scientific officer Sir Patrick Vallance at 5pm

Earlier today Professor Wendy Barclay, head of G2P-UK National Virology Consortium, a new project set up to study the effects of emerging coronavirus mutations, said one Brazilian variant of coronavirus has been detected in the UK.

She said: “There are two different types of Brazilian variants and one of them has been detected and one of them has not.”

She added: “In the databases, if you search the sequences, you will see that there is some some evidence for variants from around the world, and I believe including the Brazilian one, which probably was introduced some time ago.

“And that will be being traced very carefully.”

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Downing Street said it acted “as quickly as possible” to impose the ban on travellers from South America, with the concerning Brazilian strain possibly posing a “significant risk to the UK”.

The Prime Minister’s official spokesman said: “It’s obviously right that we continue to look at different variants and take action accordingly.

“As soon as we identified this variant our teams were quickly working on this and, given that we know this could pose a significant risk to the UK, we acted as quickly as possible, which is why you’ve seen this travel ban from those countries enacted quickly.”

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Downing Street has said evidence currently suggests the concerning new Brazilian variant of coronavirus may be more transmissible but does not affect vaccines.

The Prime Minister’s official spokesman said scientists at the Government’s Porton Down research facility are investigating the new strain.

“As with some of the other variants we’ve seen, the Kent variant and the South Africa variant, evidence does suggest that it may be more transmissible,” he added.

“More research is required to confirm this and Porton Down will conduct that research but current evidence does not suggest that the strain causes any higher mortality rate or that it affects the vaccines or treatments.”