The mutant coronavirus variant which emerged in the south of England may be more deadly than the original strain, scientists have warned.
The Government’s chief scientific adviser Sir Patrick Vallance said that while there was still a “lot of uncertainty” around the data, it was a matter “of concern” that as well as spreading more quickly, the mutant strain could also lead to more deaths.
He also told a No 10 news conference that there was some evidence that coronavirus variants which had appeared in South Africa and Brazil may be less susceptible to approved Covid-19 vaccines than the original strains.
Boris Johnson warned that further measures could be required to stop the new variants entering the UK following the decision to suspend all the Government’s travel corridors.
“We may need to go further to protect our borders. We don’t want to put that (efforts to control the virus) at risk by having a new variant come back in,” he said.
His warning came as England’s chief medical officer Professor Chris Whitty said that while infections were falling and hospital admissions were beginning to “flatline” – the situation across the country remained “extremely precarious”.
“A very small change and it could start taking off again from an extremely high base,” he said. “If that happened again, we would be in really, really deep trouble.”
Sir Patrick suggested the new variant could increase the mortality rate by nearly a third for men in their 60s who have Covid-19.
For a thousand people in that group who became infected with the old variant, roughly 10 would be expected to die – whereas with the new variant it might be 13 or 14, with similar increases in mortality rates across the age ranges.
“I want to stress that there’s a lot of uncertainty around these numbers and we need more work to get a precise handle on it, but it obviously is of concern that this has an increase in mortality as well as an increase in transmissibility, as it appears of today,” he said.
He said that while there was growing evidence that the vaccines would be effective against the UK variant, there was uncertainty over how well it would work against those from South Africa and Brazil.
“We know less about how much more transmissible they are. We are more concerned that they have certain features that might (make them) 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 stressed the evidence remained uncertain and that there was no sign the South African or Brazilian variants had any “transmission advantages” over those in the UK and so would not be expected to spread more quickly or “take over”.
Earlier, footage emerged of an online briefing by Health Secretary Matt Hancock for travel industry executives in which he suggested the South African variant could reduce the efficacy of the vaccines by about 50%.
“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,” he said.
The latest Government figures showed a further 1,401 people had died within 28 days of testing positive for Covid-19 as of Friday, bringing the UK total to 95,981.
Prof Whitty warned it would be some weeks before there was a fall in the numbers of hospitalisations, while the peak of deaths “may well be still in the future”.
Mr Johnson said there could be no easing of the lockdown restrictions in England until it was clear the vaccination programme was working.
He said the rollout was continuing at an “unprecedented rate” with a record 400,000 jabs delivered over the preceding 24 hours, taking the total to have received a first dose across the UK to 5.4 million – amounting to one-in-10 of the adult population,
“I think the most important thing is we’ve got to be in a position where the rate of infection of the virus is not still so high, and it’s very high right now,” he said.
“So, for unlocking just to lead to another big rebound, I think that would be the wrong thing, the wrong way, to approach this.”
Earlier scientists advising the Government said the reproduction number – the R – for coronavirus has fallen to below 1 across the UK, suggesting a retreating epidemic.
A subgroup of the Scientific Advisory Group for Emergencies (Sage) put the R – which represents how many people an infected person will pass the virus on to – at 0.8 to 1.0, down from 1.2 to 1.3 last week.
The Scientific Pandemic Influenza Group on Modelling (Spi-M) said the number of new infections was now shrinking by between 1% and 4% every day.