New cases of the UK variant B117 show it has evolved further and has mutation E484K (see post). This mutation probably makes our antibodies (from existing vaccines & earlier infection) somewhat less effective against the virus. E484K is a major reason why the South Africa variant B1351 is such a threat, and we need to worry about this new mutated B117 for the same reason. It appears to be very rare right now (known only from a few cases in the UK) and I hope we can eradicate it. But we sequence very little, so similar evolution may be happening in other places and we wouldn't know.
Also, more evidence accumulates that the UK variant is more lethal than earlier ones, with about a 65% increase being most likely.
Vaccines ARE still effective, especially in protecting against severe disease and death. Get vaccinated as soon as you can.