Covid-19: What we know about the 'new variants of concern'

Paris - They are more contagious and more deadly, but researchers say far beyond that.

Several coronavirus variants with the potential to be more transmissible have caused global concern over whether existing vaccines will still protect the world from a virus that is constantly mutating.

Here’s what we know about them and what this implies for the Covid-19 pandemic.

What’s mutation of virus?

Viruses continually mutate as tiny errors are introduced each time they replicate. The SARS-CoV-2 virus is no different, and has already undergone several thousand mutations since it emerged in humans in late 2019.

Of the current known variants, three are particularly worrying: Those initially detected in southeast England, South Africa and in travellers from Brazil arriving in Japan.

They circulate respectively in 125, 75 and 41 countries, according to a recent update from the World Health Organisation.

Variants of concern and variants of interest

It has designated them “variants of concern” because of their increased transmissibility and/or virulence, which worsens an epidemic and makes it more difficult to control.

There are also several “variants of interest” — first identified in Scotland, the United States and Brazil — under surveillance because of potentially problematic genetic characteristics.

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Finally, many other variants are circulating, which are being tracked by the scientific community through genetic sequencing.

“The coming weeks and months will tell us whether they fall into the worrying category of variants that spread rapidly, or if they will remain as variants that circulate weakly,” Etienne Simon-Loriere, head of viral evolution at France’s Pasteur Institute, said.

All variants are categorised according to the mutations they have acquired. Each occupies its own spot in the genetic family tree of SARS-CoV-2.

It’s a tree that is constantly growing branches.

Naming the variants

Unlike events like viruses themselves, variants do not have a recognised international naming system, so their official titles tend to be somewhat technical.

For example, the strain that appeared in England is called 501Y.V1 or VOC202012 / 01 and belongs to the line B.1.1.7.

Given this, people have resorted to the snappier terms “English variant”, “South African variant” and so on, although this has caused concerns that certain countries will be stigmatised.

Viruses normally accumulated mutations over time so the appearance of variants is not at all surprising.

Most of these changes will not have “a direct benefit to the virus or other public health impacts”, according to the WHO.

It all depends on the mutations they carry.

The English, South African and Brazilian variants all share a particular mutation — named N501Y — that is thought to increase infectiousness.

The mutation occurs on the virus’ spike protein, which almost certainly makes it more effective at binding with human receptor cells.

And the South African and Brazilian variants carry another mutation, E484K, suspected of reducing the immunity acquired either by a past infection (with therefore an increased possibility of reinfection), or by vaccines.

They are more infectious

The three “variants of concern” are all understood to be more infectious.

The WHO estimates that the English variant is between 36 per cent to 75 per cent more contagious, while the South African strain is thought to be 1.5 times more transmissible.

It said data for the Brazil variant, known as P.1, is still preliminary, but a recent study of health data in the city of Manaus where the variant has spread widely had suggested it could be 2.5 times more contagious than previous strains.

For the moment, estimates of transmissibility are largely based on observations about how fast a variant spreads.

But given that infection rates depend on a variety of factors such as social distancing measures, it can be difficult to quantify the potential increase in transmissibility.