The Government was right to share early data suggesting that the UK variant of the SARS-CoV-2 virus may be associated with increased mortality, scientists said today.
On Friday, Prime Minister Boris Johnson announced that the B.1.1.7 variant first identified in London and the South East of England was partly responsible for increased pressure on the NHS.
He was backed by Sir Patrick Vallance, the UK Government's chief scientific adviser, who said: "It is spreading 30% to 70% more easily than the old variant."
Sir Patrick said that: "If you took a group of 1000 infected men in their 60s, roughly 10 would die. But with the new variant, roughly 13 or 14 of that group might be expected to die."
Data Uncertainty
The latest analysis of the B.1.17 variant was explained in a paper from the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) published last Thursday.
Members of NERVTAG have admitted that there is uncertainty over the reliability of the data.
However, in a briefing hosted today by the Science Media Centre, three members of the group confirmed that their findings were "statistically significant".
"If we did not say something about it then I think you'd be criticising the Government for not saying something about it and trying to sweep it under the carpet," said John Edmunds, professor in the Centre for the Mathematical Modelling of Infectious Diseases at the London School of Hygiene and Tropical Medicine (LSHTM).
The NERVTAG analysis was based on four studies that involved 2583 deaths among 1.2 million tested people.
According to modelling by the LSHTM, the relative risk of death was 1.35 within 28 days of testing (95% confidence level, 1.08-1.68). Risk of mortality was consistent across age groups.
Analysis by Imperial College London suggested a mean ratio of case fatality rates between 1.36 (95%CI 1.18-1.56) and 1.29 (95%CI 1.07-1.54) depending on the method used.
Although a retrospective cohort study by Public Heath England had initially reported a relative risk of 1.00 (95% CI 0.58 – 1.73), updated linkage found the risk ratio increased to 1.65 (95%CI 1.21-2.25).
However the committee stated: "The absolute risk of death per infection remains low."
"There is some uncertainty in the data, which we've clarified in the paper, and there's ongoing work to look at additional ways of looking at the risk of death and the risk of hospitalisation, and the data will become clearer in the next few weeks," said Peter Horby, professor of emerging infectious diseases at the University of Oxford, and chair of NERVTAG.
"It's certainly not the case that this is a more benign [variant of the] virus," added Graham Medley, professor of infectious disease modelling at the LSHTM.
A 'Sobering' Analysis
Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, described the latest study as "sobering".
He commented: "We don’t yet know whether the mutations in the spike protein or other parts of the coronavirus affect the ability of antibodies to tag the virus for destruction by white blood cells. Neither do we know the extent to which T cell immunity is affected.
"What we do know is that the variant is more able to bind to our cells, which could provoke a stronger overreaction by the immune system, which causes the worst disease, and can be fatal."
Lawrence Young, a virologist and professor of molecular oncology at Warwick Medical School, said: "The report highlights that there is currently no indication of increased risk of hospitalisation in individuals infected with the variant virus which would be expected if infection is more severe."
He added: "We need more information before jumping to firm conclusions."
