Coronavirus: South African and Brazilian variants

Recently in the news we’ve heard a lot about new coronavirus variants from South Africa and Brazil. These new variants come swiftly on the heels of the new UK variant that we’ve also heard so much about. Should we be concerned? 

Variants of concern

There are thousands of variants of coronavirus around the world, but 3 – the UK variant, the South African variant and the Brazilian variant – have been given ‘variant of concern’ status by scientists.

Variants arise when errors – mutations – are made when the virus’ genetic code is copied, when the virus replicates. Many of these mutations make no difference to the structure of the virus, some give the virus a disadvantage and others give what we call a ‘selective advantage’. When a mutation that provides a selective advantage arises that variant becomes more widespread and may then be identified as a variant of concern.

We discussed the UK variant – scientific name B.1.1.7 – earlier this week. The UK variant spreads more easily, and early evidence suggests that people who catch it may be more likely to die from it. However, it doesn’t seem that the changes in the UK variant change our immune response to it. Evidence suggests that people who have natural immunity through having had previous variants of coronavirus are protected from this variant, as will people who have immunity through a coronavirus vaccine.

What do we know about the South African and Brazilian variants?

The South African variant – B.1.351 – emerged in October 2020 in South Africa and has since been identified in several countries around the world, including the UK. There is early evidence of it spreading in the UK, as some people who have it have no history of travel to South Africa.

The Brazilian variant – P.1 – was identified more recently, initially in Brazilian travellers to Japan in January 2021, although it is thought to have emerged in Brazil last summer. 

These variants have led to plans to tighten UK quarantine rules for people coming from some countries, and some local areas in the UK are increasing their coronavirus testing response to cases of the South African variant.

What is different about these new variants?

Although both the South African and Brazilian variants have arisen independently of the UK variant, one mutation – N501Y – is present in all 3 variants of concern. This mutation leads to a change in the shape of the spike protein in a way that scientists think improves the UK variant’s ability to access our cells. This mutation may be why the UK variant is easier to catch than previous variants, and the possible increased chances of dying.

Although the South African and Brazilian variants have both spread rapidly in the places they first arose, there is not yet evidence of whether they are easier to catch. There is also no evidence that people who catch the South African or Brazilian variants are more likely to die than people who catch other variants. It is too early to say whether this is because they don’t differ from previous variants in these ways or is just because they haven’t been studied closely enough yet.

As well as the mutation the South African and Brazilian variants share with the UK variant, they also share some mutations not seen in the UK variant. Early evidence suggests the mutations the South African and Brazilian variants share may change the virus so that it is less recognisable to the immune systems of people who’ve had previous variants of coronavirus.

This could mean our immune responses – due to either having had previous variants of coronavirus, or from vaccination – may not be as good at protecting us against the South African and Brazilian variants. Again, this is an area where information is still emerging, and the picture is very uncertain.

Why do the variants of concern share so many mutations?

The 3 variants of concern have all emerged separately from each other. However, they each have some identical mutations in common. The fact that some of the same mutations are seen in the 3 variants of concern is an example of ‘convergent evolution,’ where a mutation arises more than once, independently. If such a mutation becomes widespread it suggests that the mutation makes is easier for the variant to survive, replicate or spread, and having the mutation is an advantage for the virus.

A very new example of convergent evolution is that one of the mutations the South African and Brazilian variants share – E484K – has arisen independently in the UK variant in a small number of cases in the UK. Although this version of the UK variant is not yet widespread, scientists are keeping a close eye on it.

What if the vaccines work less well?

If coronavirus vaccines are less effective against the South African and Brazilian variants it remains important to take up the offer of a vaccine. The vaccines provide very good protection against all the variants that are most widespread in the UK, including the UK variant. The vaccines will also provide some protection against the South African and Brazilian variants.

If the vaccines are found to be substantially less effective in protecting us against variants of coronavirus that become widespread in the UK, the vaccines can be altered to improve the protection they provide. Work to adapt the Oxford/AstraZeneca vaccine has already begun.

The emergence of these 3 variants of concern is, however, a useful reminder to us all that vaccination alone is unlikely to end the coronavirus pandemic. The more the virus replicates, the more chances there are for further variants of concern to arise. To minimise the chances of this, we need to do what we can to reduce the spread of coronavirus.