How many variants of covid-19 are there and which are the most deadly?
The Delta variant has become the dominant strain of coronavirus in many countries around the world but it is far from the only mutation to have been spread widely.
In recent months the Delta variant of covid-19 has risen to prominence in the United States and across the world as health authorities are forced to reshape their protocols to mitigate the threat of the new more infectious strain.
However the Delta variant is far from the only mutation of the coronavirus to have arisen during the pandemic. There have been roughly 200 million cases of covid-19 and with so many transmissions there is the risk that the virus will mutate, which can lead to new variants if the alterations allow it to survive and reproduce more effectively.
Which are the four variants of concern?
To illustrate the different level of threat posed by each of the covid-19 variants, the Centers for Disease Control and Prevention have created a three-tier scale of severity.
‘Variant of interest’ is the lowest of those levels, with variants typically being linked to localised clusters but having little prevalence or expansion more broadly.
The most severe category is the ‘variant of high consequence’, which is used to describe a variant which has proved capable of defeating prevention measures or medical intervention, such as vaccines. Fortunately, there are no variants which currently fit these parameters.
The other category is the ‘variant of concern’ which currently comprises four variants, including Delta. These are typically more contagious, but are not thought to be more dangerous and can still be mitigated by existing measures and pharmaceuticals.
The four variants of concern are:
- Alpha (B.1.1.7), first identified in the UK, now detected it at least 50 countries
- Beta (B.1.351), first identified in South Africa, now detected in at least 20 countries
- Delta (B.1.617.2) – first identified in India, now detected in at least 130 countries
- Gamma (P.1), first identified in Brazil, now detected in at least 10 countries
Are the variants of covid-19 more dangerous?
All four of the variants of concern have an altered spike protein, the characteristic which allows the virus to attach itself to human cells, which have made them more transmissible. Delta in particular is known to be very contagious, thought to be due to the L452R mutation to the spike protein.
The other variants of concern, Alpha, Beta and Gamma, all share the N501Y mutation which is believed to make them spread more easily. The latter two also contain a mutation called E484K which appears to allow it to bypass some of the body’s natural immune defences.
However, while the variants can be more contagious they are not thought to be any more dangerous to those who become infected than the original strain.