The WHO opinion on the coronavirus variants detected in the United Kingdom, South Africa and Brazil fell this Friday: its Emergency Committee called for a global expansion of genomic sequencing and data sharing, as well as greater scientific collaboration to deal with the “serious unknowns” that remain about these three variants. The number of countries and territories where the variant initially identified in Great Britain is now found stands at 50 and it is 20 for the variant identified in South Africa, but the organization considers this assessment to be probably underestimated.
These variants can only be identified by sequencing their genetic code, an analysis that is not possible everywhere. The third mutation, originating in the Brazilian Amazon and whose discovery Japan announced on January 10, is currently being analyzed and could impact the immune response according to the WHO, which mentions in its weekly bulletin “a disturbing variant”.
All three have a mutation called N501Y in common. Located on the coronavirus spike protein – a spike that allows it to enter cells – this mutation is suspected to make these variants more contagious. L’Express takes stock of the data known to date.
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Detected in November in the UK, the B.1.1.7 variant, now called VOC 202012/01, “probably” originated in the south-east of England in September, according to Imperial College London. Several scientific studies, not yet peer-reviewed and based mainly on modeling, conclude that the British variant is much more transmissible, without being more lethal.
This confirms initial assessments by the NERVTAG group of researchers (advising the UK government), which estimated that transmission is increased by 50 to 70%. Thus, according to calculations by the London School of Hygiene and Tropical Medicine (LSHTM), the British variant is 50 to 74% more contagious.
For their latest report published on December 31, researchers at Imperial College London analyzed thousands of Sars-CoV-2 virus genomes sequenced between October and December. According to two different methods, they conclude that this variant has a “significant advantage” in terms of contagiousness: 50 to 75% more contagious, or a reproduction rate of the virus (R) between 0.4 and 0.7 higher than the virus. usual. In addition, the first studies on the British variant show a greater contamination of young people under 20 years old.
Another variant, called 501.V2, is now the majority in South Africa. It was detected in samples dating back to October and then spotted in a few other countries around the world, including the UK and France.
Preliminary results for the South African variant also indicate higher transmissibility, but less data are available. Another problem arises for him: if BioNTech and Pfizer quickly ensured that their vaccine was effective against the N501Y mutation common to the British and South African variants, the latter has another specific mutation, which the manufacturers of the main vaccine administered worldwide have not been tested.
Called E484K, this mutation could theoretically help this variant “to bypass the immune protection conferred by a previous infection or by vaccination”, explained on January 4 Professor François Balloux, of University College London, cited by the organization British Science Media Center. This mutation “is the most worrying of all” in terms of the immune response, said Ravi Gupta, professor of microbiology at the University of Cambridge. Laboratory tests have shown that it seemed capable of reducing recognition of the virus by antibodies, and therefore its neutralization.
However, there is nothing to indicate at this stage that this mutation is sufficient to make the South African variant resistant to current vaccines, tempered Prof. Balloux. “Even if you decrease in efficiency, you will normally still have neutralization of the virus,” said Vincent Enouf, of the National Reference Center for Respiratory Viruses at the Institut Pasteur in Paris. “I do not think that this mutation alone is problematic for vaccines,” adds immunologist Rino Rappuoli, researcher and scientific manager of pharmaceutical giant GlaxoSmithKline. In addition, several laboratories have ensured that they are able to quickly provide new versions of the vaccine if needed.
A third mutation, originating in the Brazilian Amazon and whose discovery Japan announced on January 10, is currently being analyzed and could impact the immune response, according to the WHO, which mentions “a worrying variant”. It was discovered on two adults and two children who arrived in Japan on January 2 from Brazil, Japanese health authorities explained.
This new variant could be as contagious as those in the United Kingdom or South Africa, explained Felipe Naveca, a researcher at the Fiocruz institute who studies the mutations observed in northern Brazil. This variant of SARS-CoV-2 results from an evolution of “a viral line from Brazil, which circulates in the Amazon”, provisionally named “B.1.1.28 (K417N / E484K / N501Y)”, affirmed the Brazilian researcher Felipe Naveca. “The results suggest that the mutation detected in the B.1.1.28 variant is a recent phenomenon, probably occurring between December 2020 and January 2021,” the institute said in a statement.
An official in the Japanese Ministry of Health explained that “to further analyze the variant we must first isolate it”. “It could take between several weeks and several months (…) so it is difficult at the moment to say when we can give details” on this variant, he added.
One point is nevertheless known: it shares the same E484K mutation as the South African variant. A study published on January 6 describes the case of a Brazilian woman sick with Covid in May, then reinfected in October by this variant. This second infection, more severe than the first, could be a sign that the mutation caused a poorer immune response in the patient.
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