Boris Johnson speaks at COVID-19 press briefing

The press conference discusses the rapid spread of coronavirus in London, the Southeast, and the East of England, attributed to a new variant of the virus. This variant, analyzed by NERVTAG, is not linked to more severe illness but is significantly more transmissible, potentially increasing the R number by 0.4 or more. Although early data suggests it may be up to 70% more transmissible, there is considerable uncertainty. The situation requires immediate action based on the best available information.

What is the significance of the R value mentioned in relation to the new variant?

What actions are suggested based on the current information about the virus spread?