Maria Stuart
There has been plenty of talk about new variants of the coronavirus. Maria Stuart explains what we know so far about some of the emerging variants and the effect that they are likely to have.
What is a variant?
Viruses are constantly changing and mutating. Small variations in the genetic code of the virus can result in small changes to the proteins present on the surface. There are often many different variants of a virus circulating in the population at any one time, and this is what we are seeing with COVID-19.
Most variations of the virus are small changes with no effect on transmission or disease severity. They can even be used to track outbreaks and monitor how the virus moves through the population.
The most important variants, the ones you are more likely to hear about on the news, are when these variations result in a virus that can infect hosts more effectively, or cause greater disease severity. For COVID-19, this involves a mutation to the spike protein.
A model of the COVID-19 spike protein
Variant B.1.1.7
These spike proteins are how the coronaviruses got their name – “corona” means crown, referring to how the spike proteins on the virus surface resemble a crown. It is this part of the virus that binds to receptors on the surface of human cells (in this case, the human ACE2 receptor) and is how the virus attaches to and infects a host.
The increased effectiveness of transmission means that this variant has a selective advantage over the other variants
The first widely investigated variant, B.1.1.7 (also known as VUI-202012/01), has a mutation in the receptor-binding region of this spike protein, meaning it is more effective at binding to the ACE2 receptor, causing an increased rate of transmission.
It is this variant that is associated with the sudden and unexpected rise of cases in the South East of England over the Christmas period.
Although this strain appears to have originated in the UK, variants in South Africa and Australia evolved the same mutation independently. In all locations, the increased effectiveness of transmission means that this variant has a selective advantage over the other variants – meaning that it quickly becomes the dominant strain.
Importantly, while this variant spreads more rapidly, there is currently no evidence that it results in a more severe form of the disease.
E484K mutation
An additional mutation, known as the E484K mutation, has been seen in some B.1.1.7 samples in the UK. This is similar to what has been seen in South Africa, which has also seen this same mutation appear independently in the B.1.1.7 variant (hence this variant is sometimes referred to as the South African variant).
Not much is known about this variant yet, but some researchers have found that it is potentially more effective at avoiding the immune system, but there is no evidence it causes a more severe disease.
Will these variants affect testing?
Currently, no. Most PCR tests look for three main regions of the virus, the spike region being only one of these.
This means that currently, the mutation in the new variants are not anticipated to impact testing, and it is something that is being taken into consideration by researchers who monitor the effectiveness of the tests.
Is the vaccine still effective?
Yes! The current vaccine has been shown to be effective for both the old and new variants of the virus, and it is very unlikely that a variant will render any vaccines ineffective.
Editing the existing vaccine is much quicker and easier than developing the vaccine
This is because when you are vaccinated, your body produces a wide range of many antibodies, with different antibodies to recognize different parts of the virus. A few mutations in a few regions of the virus is not likely to impact the vaccine’s effectiveness or the immune response to the actual virus.
In the future, as more and more mutations accumulate the vaccine will need to be edited to maintain vaccine efficacy, which is a relatively simple and quick process – editing the existing vaccine is much quicker and easier than developing the vaccine in the first place!
It is important to bear in mind that coronaviruses do not mutate anywhere near as quickly or as frequently as the influenza virus for example, and so it will be a while before the technology needs to change to keep up. It should be noted, however, that some studies have shown a slight reduction in vaccine efficacy against some variants.
Conclusion
The best way to slow the speed at which new variants arise is to slow the spread of the virus and reduce the number of cases. To prevent opportunities for the virus to mutate further, remember hands, face, space; wash your hands regularly, wear a face mask, and maintain social distancing.
Maria Stuart
Featured image by Fusion Medical Animation on Unsplash. Image license found here. No changes were made to this image.
In article image by NIAID from Flickr. Image license found here. No changes made to this image.
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