LONDON (REUTERS) - Following are details of a new coronavirus variant that has been identified in the United Kingdom, given at a news conference on Saturday (Dec 19) by Prime Minister Boris Johnson, Patrick Vallance, Britain's chief scientific adviser, and Chris Whitty, the chief medical adviser.

- The new variant is thought to have first occurred in mid-September in London or Kent, in the south-east of England.

- British analysis suggests it may be up to 70 per cent more transmissible than the old variant, which could increase the reproduction "R" rate by 0.4.

- There is no evidence to suggest it is more lethal or causes more severe illness.

- There is no evidence suggesting vaccines will be any less effective against the new variant.

- The new variant contains 23 different changes, many of them associated with alterations in a protein made by the virus.

Vallance said this was an unusually large number of changes.

- It has variants in areas of the virus that are known to be associated with how the virus binds to cells and enters cells.

- The variant has spread quickly in London, the south-east and east of England, becoming the dominant form of the virus in these areas.

- In London, 62 per cent of cases were due to the new variant in the week of Dec 9. That compared to 28 per cent three weeks earlier.

- In London, the overall infection rate doubled in the last week.

- In areas where the new variant was dominant, hospital admission rates were rising quickly and previously agreed social restrictions were no longer strong enough.

- Vallance said he thought the new variant may be in other countries as well but might have started in Britain.

- The UK submitted its findings to the World Health Organisation on Friday night.