Health Secretary Matt Hancock has said the Government "would like to have more information on the new variants" of Covid-19 seen abroad, adding: "We're working on those."
Mr Hancock said that, as of Sunday morning, three quarters of all people over 80 in the UK have been vaccinated.
He told Sky News' Sophy Ridge On Sunday: "We've been learning about the virus all along haven't we and one of the critical questions for instance right now is, after you've been vaccinated how much impact does that have on how much you might transmit the virus, as well as the impact on you in terms of serious disease and that's one of the key questions that will impact on how quickly we can lift measures.
"We would like to have more information on the new variants that we've seen abroad, especially the two particular variants of concern that have emanated from South Africa and Brazil and we're working on those, but we find out more all the time."
Mr Hancock urged people to stay at home and follow the rules and said: "We should be worried enough, all of us, about this pandemic to follow the rules and it is just so important that people do.
"This morning I've come out of my formal self-isolation, I haven't actually left the house yet because I haven't needed to."
He added: "Whatever the exact nature of the UK new variant, and the scientists do think that it may be more deadly and they've put various estimates on that from about 10 per cent more deadly to a bit more than that, we are not exactly certain about how much more deadly.
"But in a way, for all of us, that doesn't matter. What matters is we've got to get this virus under control."