A new variant, sequenced in South Africa and made public on Thursday, raises the world's health authorities fears of the worst.
With a very large number of mutations, potentially more contagious than Delta, the variant is cause for concern.
20 Minutes
takes stock of the information available.
On Thursday, South African scientists made public the discovery of a new variant of the coronavirus, B.1.1.529 - or "Nu" according to the new classification.
An announcement that led to a start of panic on a worldwide scale, due to the extremely high number of mutations of this variant, but also to its speed of propagation.
It could be the first known variant of the coronavirus to impose itself in front of the Delta in population, in other words to be transmitted even faster than him.
Until then, Delta was the most contagious variant: 60% more contagious than the Alpha variant, itself 50 to 74% more transmissible than the original strain.
Faced with this worrying news, many countries, including France, have closed their borders to southern Africa (South Africa as well as neighboring countries).
A justified wind of panic?
20 Minutes
takes stock.
What do we know about the B.1.1.529 variant?
According to scientists, the B.1.1.529 variant has at least 10 mutations, compared to only 2 for the Delta.
But it is especially the South African sequencing that worries.
According to them, the variant would already represent 75% of new cases in the country.
Such a percentage, if confirmed, would mean that it is gaining the upper hand over Delta - a fact never before observed in the world -, and that it would therefore potentially be even more contagious.
Sequencing is not always an exact science: it is the reading of a population sample at an instant T, and can be even more biased if it is done inadvertently in a local cluster.
In addition, the incidence in South Africa is low, 30 times fewer cases than in France for a smaller population: a new variant can quickly give the impression of being imposed.
These doubts should not prevent a legitimate fear: “The first appearance of the variant dates from the end of September, we already have a little bit of time and hindsight.
South African scientists could have sounded the alarm at the end of October, in view of the sequencing reports, ”underlines
immuno-oncology researcher Eric Billy
to
20 Minutes
.
Does this variant reduce vaccine protection?
If it seems more contagious than the Delta variant, B.1.1.529 is also worrying because of its large number of mutations, which could - and we insist on the conditional - decrease the effectiveness of vaccine protection. Likewise, it is not yet clear whether this variant causes more severe forms or greater mortality, again a hypothesis due to its large panel of mutations.
"If it turns out that it greatly reduces vaccine efficacy, we might even have to redo new vaccines especially for this variant," worries Eric Billy.
It should be remembered, however, that even in the worst scenario where B.1.1.529 reduces vaccine protection, it should not be completely zero for all that.
In other words, it will always be more advantageous to be vaccinated than not to be vaccinated: “It is unlikely that all the effectiveness of neutralizing antibodies will be lost even in the worst case scenario.
The vaccine will remain partly useful, ”recalls the researcher.
"It is very likely that the immune escape evaluation experiments will be carried out quickly in the coming weeks," he notes, which should allow us to learn more about vaccine efficacy.
Was this scenario predictable?
Unfortunately, yes. The World Health Organization (WHO) has long warned about the poor vaccination of poor countries, potential nests with variants, and calls for Western countries to make global vaccination a priority. In South Africa, only 24% of the population received two doses of the vaccine (against 75% in France, for example). The less the population is vaccinated, the more the virus circulates, the more likely it is to mutate.
In addition, the country has one of the populations most affected by HIV in the world, with more than 15% of the inhabitants affected.
However, “a small part of the South African population due to untreated HIV is immunocompromised.
When they are infected with Covid-19, these people become a bioreactor which allows the virus to select mutations that can generate an immune escape, ”raises Eric Billy.
What can France do?
Every time a variant that is more contagious than the previous one has emerged in a country, France has ended up having it too, whether it is Alpha or Delta.
The country has already closed its borders to flights from several countries in southern Africa, but should, according to Eric Billy, extend the restriction to the entire continent, given the probable circulation of the variant.
25% of sequencing in Africa contains the Nu variant, although this figure is most likely biased, as South Africa sequences much more than other nations on the continent.
According to the specialist, France should also start sequencing on a massive scale in order to detect this variant as quickly as possible on its territory.
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20 minutes video
Covid 19
epidemic
Delta variant
Coronavirus
Health
South Africa
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