Early evidence suggests the variant of coronavirus that emerged in the United Kingdom may be more deadly, Prime Minister Boris Johnson said.
However, there remains huge uncertainty around the numbers, and vaccines are still expected to work.
The data comes from mathematicians comparing death rates in people infected with either the new or the old versions of the virus.
The new more infectious variant has already spread widely across the UK and another part of the world with Ghana also confirming a trait of the UK variant of the deadly virus