Delta Plus, what is the AY.4.2 variant, present in Great Britain and Italy-

by time news
from Cristina Marrone

The new strain accounts for 6% of sequenced cases in England and could be up to 15% more transmissible. Also present in Italy for now it does not alarm scientists

A under variant of Delta, for now called AY.4.2 (although some use the misnomer Delta Plus), under observation in particular in the United Kingdom where it represents approximately 6% of the cases sequenced in the last week in the country.

This is a rising figure, so much so that the Health Security Agency (UKHSA) has moved the new sub-strain to the under investigation category with the aim of investigating its characteristics in the laboratory and understanding whether it is more transmissible than Delta or may circumvent vaccine protection.

On 20 October the British gave the new variant the official name of VUI-21OCT-01. 15,120 cases have been confirmed in England so far, since it was first detected in July.

The mutations
I viruses are constantly changing
, most of the mutations are random and have no significant impact. Some can give the virus some characteristics such as a selective advantage than the others through one greater transmissibility, greater pathogenicity with more severe forms of disease or the possibility of circumventing the immunity previously acquired by an individual either by natural infection or by vaccination. In these cases they become a cause for concern, and must be monitored carefully.

The emergence of AY.4.2 in Britain indicates what scientists repeated over and over during the pandemic: increased transmission can create new variants. And the UK has had the highest daily rate of Covid-19 cases and deaths per million people in Western Europe since most restrictions on the pandemic were lifted in the summer.

Symptoms equal, greater transmissibility
At the moment, based on the investigations conducted so far, AY.4.2 does not appear to cause more serious disease or make current vaccines less effective and, unlike Delta, the World Health Organization does not consider it a VOC variant of concern or even a VOI variant of interest. In Denmark, another country with an excellent genomic surveillance program, prevalence has reached 2%. Other cases have been reported sporadically in Russia, Germany, Italy, Israel and the United States (less than 10 cases).

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Scientists are investigating the transmission capacity of AY.4.2. In the UK, the sub-variant has been around for months, yet it is not spreading with the explosive speed seen with the Delta strain upon its entry into Britain. Two experts Jeffrey Barrett, director of the Covid-19 Genomics Initiative at the Wellcome Sanger Institute in Cambridge, e Francois Balloux, director of the University College London Genetics Institute – said that AY.4.2 appears to be 10 to 15% more transmissible than Delta, but the data is far too uncertain and preliminary and there are no published studies yet.

The role in the rise of cases in Great Britain
Could the spread of this new sub-variant have contributed to the increase in coronavirus cases in Britain? Experts deny that AY.4.2 is the direct cause of the many cases of Covid, hospitalizations and deaths in the country, the reasons for which are actually sought more than anything else in the early abandonment of all restrictions. Francois Balloux clarified: A 10% increase in transmissibility may have caused only a small increase in cases and I don’t think it could have pushed the recent increase in infections in the UK. We are not in a situation comparable to when Alpha and Delta emerged, which were much more transmissible than any strain at the time and spread very rapidly. Here we are dealing with a potential small increase in transmissibility that would not have a comparable impact on the pandemic.More transmissible does not mean more dangerous and more virulent, added Dr. Len Horoviz, a specialist in pulmonology at Lenox Hill Hospital in New York.

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The new Delta in Italy
The new mutation also present in Italy, albeit in a rather limited number of cases. They have been made 86 sequenziamenti based on data updated to October 19, explained the president of the Higher Institute of Health (Iss), Silvio Brusaferro, who also recalled how the classic variant represents over 99% of six sequences in our country, in line with the rest of the European Union.

Delta’s sub-variant doesn’t worry us. It circulates in Great Britain and has not become predominant. It seems to be 10% more contagious, but there are no studies that support this hypothesis. was also isolated in Italy. For now we are calm and the control centers do not consider it a subject of concern and further investigation, he said Giorgio Pal, virologist, president of Aifa. Sergio AbrignaniProfessor of Immunology at the State University of Milan and member of the Scientific Technical Committee, he said to Agor: As always happens with the variants of Sars-Cov-2, even with respect to the new variant we have to look at two things. First of all, transmissibility, that is, any variant that is more transmissible than the Delta will tend to take over, but this AY.4.2 is not. The second thing to consider is whether the Delta sub-variant escapes more from the immune system and therefore also from vaccines, with the same transmissibility. But that doesn’t seem to be the case.

How is this variant of the virus different?
The most common of the Delta sub-lineages AY.4 which has given rise to two recognized sub-lineages, AY.4.1 and AY.4.2. proteina spike with which the virus infects human cells, called Y145H and A222V. Both spike mutations have been found in various other Sars-CoV-2 lineages since the start of the pandemic, but have remained low in frequency until now. The first strains carrying both mutations were sequenced in April 2020. Neither was found in any variant of concern. A222V was found in lineage B.1.177 that engulfed Europe in the summer of 2020, but careful follow-up analysis indicated that the lineage likely had no inherent advantage of transmissibility. Apparently none of the mutations appear to be a candidate for increased viral transmissibility, however, mutations can have different, sometimes unexpected effects, depending on the strain in which they are present.

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The Delta plus
Last June, the spread of a new variant of the coronavirus called Delta Plus, detected for the first time in India and which had the mutation, raised concern K417N, common to Beta, widespread in South Africa which had demonstrated partial immune evasion to vaccines.

The strain is called B.1.617.2.1 or AY.1, from where the further mutation we are talking about these days, AY.4.2, is derived from.

A study just published in Nature that studied Delta Plus in the lab concluded that the variant is confirmed to be more resistant to mRNA vaccines than the original virus, but without differences with the Delta and also the ability to enter human cells is no different than the Delta.

October 23, 2021 (change October 24, 2021 | 09:42)

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