In December 2020 the blog piece “The New Variant of COVID-19” (click here to read) addressed the issue of what a virus mutation is and if we should be concerned about a new variant emerging in London and the south east of England. At that time there was no clear evidence as to whether the new variant would prove more deadly but it was proving itself to be more infectious.
At the Downing Street briefing on 22 January 2021, Prime Minister Boris Johnson announced that the new variant of the virus was now known to be not just more infectious but also more lethal than the original. Named B117, it was reported to be up to 70% more transmissible and have a 30% higher mortality rate than the original variant that caused the first wave of the pandemic in the UK. (1)
B117 has already been detected across the world and in the USA health officials have announced that they expect it to be the dominant variant there by March 2021. (2)
The evidence of increased mortality from B117 came from a new UK government group, the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) which carried out data studies on cases and deaths from COVID-19.
Each analysis showed different results but all of them showed a higher mortality risk among people infected with the B117 variant. The figure of a 30% increase in mortality rate was reached by averaging the results of each study. (3)
Research is ongoing as to why the new variant is both more infectious and more lethal but scientists have established that the B117 variant binds more strongly to human cells.
"That is the most plausible biological explanation for (both) the observed increase in transmissibility and, possibly, the increase in severity that we might be seeing," according to Professor Peter Horby, who specialises in emerging infectious diseases at Oxford University and is the chair of NERVTAG.
At the 21 January briefing, Sir Patrick Vallance, the Chief Scientific Adviser to the UK Government, gave an example to aid understanding of the situation explaining that if the original variant killed 10 out of every 1000 COVID-19 cases, the new variant was killing 13 to 14. (It is important to remember that he was using these numbers to aid understanding, not quoting that particular day’s figures.) (4)
However he also said that for those seriously ill in hospital with either variant, the outcome and chance of death remained the same.
At first glance these two statements seem to contradict each other. If the death rate for both variants is the same, how can one cause more deaths than the other?
It becomes clearer when using actual numbers to aid understanding (again, the figures below are just for explanation and not indicative of any one day's actual figures).
For every 1000 people who become ill with the original COVID-19 variant imagine that 20% are hospitalised but for the new variant of the virus for every 1000 cases 40% are hospitalised.
Once in hospital the chance of dying is 20% for both variants, neither is better nor worse than the other.
So for the original variant 20% of 1000 cases are hospitalised which is 200 people. Of those, 20% unfortunately die which is 40 people.
With the new variant 40% of 1000 cases are hospitalised which is 400 people. Of those 20% die which is 80 people.
The number of deaths per 1000 cases is higher with the new variant than the original variant (80 deaths versus 40 deaths) but there has been no change in the percentage of the hospitalised patients who die (both 20% of those hospitalised.)
The new variant is causing more cases of serious illness that require hospitalisation and this in turn leads to more deaths. Once seriously ill in hospital the risk of dying is 20% irrespective of which variant is at play but the new variant is more likely to put you in hospital than the original variant.
Sir Patrick also observed that "There are some important limitations to the data on which these analyses are based. A relatively small number of people were included in the analyses and from a small number of settings, so more data is being collected and the position will become clearer over the coming weeks." (5)
For example, there may be differences in who is catching the new variant compared to the old variant which could skew the figures. At the start of the outbreak, the cases detected were all hospital ones only as there was no community testing. COVID-19 cases and deaths occurring in the community may have gone undetected or been attributed to other causes.
What about the Vaccine and New Variants?
As well as the B117 variant identified in the UK, several others have emerged in other countries.
In South Africa one, now named as B1351, and in Brazil two, named P1 and P2 respectively, have been identified.
All the variants have mutations (or changes) in the protein spikes that project from the virus surface. These spikes are the structure the vaccines target so there is concern that changes in the spikes may render the vaccines less effective.
Most mutations cause such minor changes in a virus that they have little overall effect. However sometimes the mutation allows the virus to go unrecognised by the immune system, so called “escape mutants”, which means the vaccine that worked pre-mutation is no longer as effective.
Scientists know that mutations in the spike protein could emerge that affect the vaccine’s ability to work. However, the human body makes many different types of antibody in response to either infection or vaccination - known as a polyclonal response – which means it is highly unlikely a new variant will not be recognised by any of the body’s antibodies. (6)
None of the current coronavirus variants have rendered the approved COVID vaccines ineffective but work is ongoing to see if they reduce the effectiveness of the vaccines. The South African variant has three significant mutations and is the one of most concern at the current time. However, even if a vaccine becomes “less effective” it may still be good enough to prevent disease. Pfizer has said its vaccine remains effective against the South African variant. (7)
Moderna has said that its vaccine is effective against the UK variant but gives less protection against the South African one. Moderna is currently developing a booster shot to address this. (8)
Work has already begun at Public Health England’s Porton Down laboratory to assess the impact of the new variants on the Oxford-AstraZeneca vaccine. The processes for adjusting the vaccine to keep it effective against new variants are already being out in place. (9)
On a more positive note it is possible for scientists to update the genetic sequence of the spike protein in vaccines at regular intervals to keep them as effective as possible. We already change the flu vaccine each year as the infectious strain of influenza changes. We may need to do the same with the COVID-19 vaccines.
