Sars-Cov-2, what are the characteristics of the South African variant

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An analysis by Pfizer and University of Texas Medical Branch researchers, elaborated on the blood of immunized people, explains that the vaccine developed by the US giant together with the German biotech BioNTech would also be effective against the different variants identified in recent months in the genome of the virus. Including that present in the so-called English and South African variants, as well as other 15. But it is in any case essential to know more about the Sars-CoV-2 variant, the South African one, which would be responsible for a surge in cases also in the African country.

Is called 501.V2 and among the different variations with respect to the genome of the reference lineage it includes, as mentioned, the notorious mutation N501Y which concerns the spike protein of the coronavirus, the one that the pathogen uses to bind to our cells and attack them. Compared to the variant identified in England, however, it differs in several genetic aspects including the mutation E484K. It would be precisely the variant responsible for the second wave in the country, identified up to 90% of the samples of the genetic sequences analyzed since mid-November. Overall the variant counts 21 mutations, nine of which concentrated in the spike. The most worrying would be E484K, which like the N501Y intervenes on receptor binding domain, not only a key portion of protein S but also a site where neutralizing antibodies induced by infection or vaccination bind to the virus to eliminate it. That is why such mutations are always worrying about the effectiveness of vaccines.

Confirmed last December 18, the variant 501.V2 would be in circulation already from the end of August. Cases of this particular combination of mutations have been identified in several countries, from the UK to Japan via Switzerland and Finland to the Netherlands a few days ago. Investigations are still ongoing but the preliminary results would infer the ability to cause infections characterized by a ‘high viral load, perhaps linked to one more marked contagiousness, even superior to the English variant. However, the WHO reiterates that for now “there is no clear evidence that the new variant is associated with more severe forms of disease or worse outcomes”.

The scientific community seems confident that even in the case of E484K vaccines can work with the same effectiveness, giving protection to all variants of the virus that contain it. As is known, in fact, vaccines stimulate the production of different types of antibodies in any case able to bind to protein S despite some worrying mutations. This does not prevent the effectiveness from turning out to be lower, for example, but more will be known in a few weeks. On the other hand, the virus, which also appears stable as a whole despite being of the Rna type, it will continue to change: most of the changes are actually insignificant but sometimes, as in these cases, some changes may emerge that can modify a series of characteristics. For this vaccination campaigns must be fast and massive, to contribute together with the restrictive measures to decrease circulation and, with it, the opportunity for the virus genome to change at too high speeds and frequencies, capable of affecting the effectiveness of the findings available up to that moment. Thus favoring the selection of variants resistant to neutralizing antibodies

In addition to containing the epidemic we should sequenziare in a more frequent and structured way i virus genomes identified in Italian patients or patients present in Italy to make us aware of exactly what are the variants in circulation. The association Biologists for science for example, he launched an online appeal “for the establishment of a national network of laboratories to deal with the genomic surveillance of Sars-Cov-2”. On the other hand, the English variant has taken this journalistic name for the sole fact of having been identified in Great Britain thanks to the high capacity of analyzing genomes in that country but, in fact, it is by no means certain that it has emerged overseas. Italy also needs a system that allows us to sequence a significant sample of the genomes of the virus identified in all positives. With the spread of vaccines, the virus will perhaps circulate less, it is true, but more resistant variants could begin to develop which, perhaps because they are more contagious, would force us to increase times and coverage to obtain herd immunity, without lightening too much the pressure on health systems.

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