British Prime Minister Boris Johnson has said there is some evidence that the new variant of coronavirus first identified in the UK may be linked to a higher death rate.

Mr Johnson told the Downing Street press conference: "I must tell you this afternoon that we've been informed today that in addition to spreading more quickly, it also now appears that there is some evidence that the new variant, the variant that was first identified in London and the South East, may be associated with a higher degree of mortality."

Ireland's Chief Medical Officer Dr Tony Holohan said yesterday the variant will become the dominant strain of the virus here over the next few weeks.

That variant accounts for over 60% of the most recent cases analysed in Ireland, he said.

Patrick Vallance, the British chief scientific advisor, said evidence is growing from multiple sources that vaccines will work against the UK coronavirus strain.

"There's increasing evidence from laboratory studies that the variant in the UK will be susceptible to the vaccines.

"There's increasing confidence coupled with a very important clinical observation that individuals who have been infected previously and have generated antibodies appear to be equally protected against original virus and new variant." 

Professor Vallance said the coronavirus variant, which originally emerged in Kent, is "a common variant comprising a significant number of cases" and transmits up to 70% more easily than the original virus.

He told a Downing Street press conference: "We think it transmits between 30% and 70% more easily than the old variant. We don't yet understand why that is the case.

"It doesn't have a difference in terms of age distribution ... it can affect anybody at any age, similarly to the original virus."

He added that among people who have tested positive for Covid-19, there is "evidence that there is an increased risk" of death for those who have the new variant compared with the old virus.

Prof Vallance cautioned, however, that this is based on evidence which is "not yet strong" and there is "no real evidence of an increase in mortality" among those hospitalised by the variant.

"These data are currently uncertain and we don't have a very good estimate of the precise nature or indeed whether it is an overall increase, but it looks like it is," he added.

Vaccine efficacy for variants

Prof Vallance said the variants that originated in Brazil and South Africa are of more concern than that of the UK, because there are fears they may be less susceptible to vaccines.

He said: "We know less about how much more transmissible they are. We are more concerned that they have certain features that they might be less susceptible to vaccines.

"They are definitely of more concern than the one in the UK at the moment, and we need to keep looking at it and studying it very carefully."

He said it was too early to know whether the variant from South Africa was more resistant to vaccines.

Prof Vallance said: "We will find out how effective the vaccines are against this.

"It is the case that both the South African and Brazilian identified variants have more differences in shape which might mean they are recognised differently by antibodies.

"I think it is too early to know the effect that will have on the vaccination in people and it is worth remembering that the response of the vaccine is very, very high antibody levels, so they may overcome some of this.

"We don't know, but there's obviously a cause for concern." 

Meanwhile, British Health Secretary Matt Hancock said "there is evidence in the public domain" that the South African coronavirus variant "reduces by about 50%" vaccine efficacy.

In what is reportedly a recording of an online webinar with travel agents this week, obtained by MailOnline, he said: "There is evidence in the public domain, although we are not sure of this data so I wouldn't say this in public, but that the South African variant reduces by about 50% the vaccine efficacy."

He added: "We're testing that and we've got some of the South African variant in Porton Down (testing laboratory), and we're testing it. We've got a clinical trial in South Africa to check that the AstraZeneca vaccine works.

"Nevertheless, if we vaccinated the population, and then you got in a new variant that evaded the vaccine, then we'd be back to square one."

Three cases of the strain that originated in South Africa have been detected in Ireland to date.