Why are we so interested in this new variant of SARS-CoV-2?
Virus mutations are nothing new; we get new flu vaccines each winter precisely because flu viruses regularly mutate. RNA viruses such as SARS-CoV-2 are particularly prone to mutations – more so than DNA viruses.
The various lineages of SARS-CoV-2 are accumulating mutations at the rate of 1 – 2 per month (1). There are hundreds of mutations known, across a number of ‘lineages’ – many are now the focus of careful research. While no one is surprised that SARS-CoV-2 has mutated, the variant drawing our attention currently, named ‘lineage B.1.1.7’ (also referred to as VUI-202012/01, denoting that it is the first Variant Under Investigation in December 2020), has prompted concern due to how quickly it has become a prevalent strain among newly detected cases in parts of the UK.
When/where was this variant first found?
B.1.1.7 was first detected in the COGUK (COVID-19 Genomics) UK surveillance database in Kent on 20 September and London on 21 September 2020, a total of 1623 ‘cases’ (individual genomes within the dataset) had been found by 15 December – 4 of these are from outside of the UK, meaning that scientists consider it probable that this variant in a mutation that first occurred in the UK.
What is different in this variant?
A key issue with B.1.1.7 is the number of mutations that it has accrued prior to its detection in the dataset - 17 amino acid replacements since September 2020. Among these, changes to the genes coding for the receptor-binding domain (RBD) appear to have the potential to increase the virus’s ability to bind to the human ACE2 receptors (present in the respiratory system), and to also affect the ability of the virus to evade the immune system’s responses (2,3). Other changes may increase the variants ability to mutate more readily in the future.
What do these changes mean for the new variant?
The evidence remains relatively limited, so we are not currently able to say with confidence that these changes are causing increased transmission rates, or that this variant is more likely to avoid the immune response; we can only show that there is a correlation between the growth of B.1.1.7 prevalence in the samples, and a significant increase in the R-value of the virus generally in those areas with the higher B.1.1.7 variant.
Estimates suggest that the new variant may be associated with an increase in R-value of between 0.39 and 0.93, which would mean that it had a growth rate 71% higher than other known variants. While the emerging evidence suggests that B.1.1.7 may be more infectious, we don’t have any evidence yet that it causes more severe disease.
What should we do about the new variant?
As individuals, the new variant should encourage us all to ensure that we are following the established behaviours to reduce the risk of becoming infected or spreading the virus to others. Washing your hands carefully and regularly remains an important measure. Disinfecting surfaces and avoiding handling objects likely to have been touched by others is also an important strategy. Wearing masks and limiting social contact, are still vital to reducing the spread of the virus the new variant.
As clinicians, vigilance on guidance on PPE and disinfection protocols is especially vital if your practice is in one of the areas where the new variant is prevalent.
As yet, we don’t have the evidence we need to know if the new variant will be able to evade the vaccines. It is likely that they will be effective against it (REF), but even if they aren’t both of the new vaccines for SARS-CoV-2 are of a type that can be readily ‘tweaked’ to produce new versions, so it is very likely that they can be updated to become effective against B.1.1.7.
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