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The enthusiasm for starting the vaccination campaign against SARS-CoV-2 coronavirus in Great Britain and the United States – and which in the next few days will also start in the 27 countries of the European Union – was overwhelmed from the media point of view by the circulation of the so-called “English variant” of the pathogen Pressure – called B.1.1.7 – which is spreading rapidly and uncontrollably in south-east England, and which has now been isolated in other countries as well. The main concerns related to this variant are related to the main transmissibility (to clarify, although the clues are significant), the potential risk that it could trigger a COVID-19 more severe, although there are currently no differences in symptoms – and the ability to evade the protection offered by “very fresh” vaccines (such as Pfizer just approved). In short, this mutated variant of the coronavirus has fallen like a meteor on the foundations of the renewed trust built thanks to the vaccine, setting off chain reactions that are leading to the UK’s isolation. Stop a flights and trains, mandatory quarantine for returning travelers and “hunting” the carpet contacts are some of the initiatives implemented. But what exactly do we know about B.1.1.7? Do we really have to worry? This is what the scientists say and where the research is.
Mutations are normal
Although the strain is under attack by health authorities and institutions, it is first of all necessary to emphasize that at the moment there is no absolute certainty about its “improved” characteristics, therefore, scientists preach with caution and common sense, indicating they need time to analyze the data. and find all relevant confirmations. As specified in a press release from researchers at COVID-19 Genomics UK (COG-UK), a British organization dedicated to the analysis and sequencing of the SARS-CoV-2 genome, viruses mutate and pandemic pathogen is no exception. According to the phylogenetic studies carried out to date, SARS-CoV-2 accumulate 1-2 mutations per month, while it replicates in infected people. “This means that many of the genomes sequenced today differ by about 20 points from the first genomes sequenced in China in January, but there are also many variants with fewer modifications in circulation,” the authoritative scientific journal Science noted in an editorial dedicated to the variant. in English.
17 mutations in the English variant
This evolution of the coronavirus can be followed practically step by step, said the genomicist of the University of Birmingham Nick Loman, precisely because its genome it is constantly under close surveillance. What makes variant B.1.1.7 unique compared to the others are two factors: the high number of mutations detected, up to 17 (14 amino acids e 3 eliminations) acquired simultaneously; and the location of most of them (8) in the protein S OR Spike, the glycoprotein that the coronavirus uses as a “biological hook” to bind to ACE-2 receiver of human cells, break the cell wall, insert the viral RNA inside and start the process replication, underlying the infection (known as COVID-19). Due to its crucial role in infection, protein S represents the main purpose of vaccines, which aim to develop immunity Against. If indeed it is ours immune system It recognizes it as an “enemy” and attacks it, prevents the virus from “attaching itself” to human cells and neutralizes it. But if the protein changes, the vaccine could be ineffective, just as it could make more transmissive me lethal (or less lethal) virus. Since B.1.1.7 has so many mutations in protein S, which makes up the surface of the virus in the form of a “parasol”, and has spread so rapidly, it is natural that scientists have attacked it. But at the moment, as noted, there is no certainty about its “enhanced” capabilities.
Estimated transmissibility greater than 70%
Mutations related to coronavirus protein S, as specified in a press release from the European Center for Disease Prevention and Control (ECDC – European Center for Disease Prevention and Control), are as follows: deletion 69-70; deletion 144; N501Y; A570D; D614G; P681H; T716I; S982A and D1118H. From preliminary investigations it is estimated that due to them the English variant has a transmissibility over 70 percent, with a potential increase in the Rt index of 0.4. It is precisely because of these alleged characteristics that several governments -among them the Italian- have decided to suspend the air connections with the UK and create a blockade contact tracking at risk. As stated by Chief Scientific Advisor Patrick Vallance, B.1.1.7 first appeared in an isolated virus on September 20 and, as of mid-November, represented around 26 cases. “For the week that started December 9, these numbers were much higher. So, in London, more than 60 percent of all cases were due to the new variant ”, specified the scientist. Of the mutations mentioned, the ones that are of most concern and that could be closely related to the boom in infections are the N501Y, “Which has already been shown to increase the degree of protein binding to the ACE2 receptor, its point of entry into human cells”, and 69-70 deletion, “Which leads to the loss of two amino acids in the Spike protein and has been found in viruses that eluded the immune response in some immunosuppressed patients. “In the research” Preliminary genomic characterization of an emerging SARS-CoV-2 lineage in the United Kingdom defined by a new set of spike mutations “carried out by the CoG-UK, it is emphasized that the effects of mutation should also be thoroughly analyzed P681H, which “is immediately adjacent to the cleavage site of the furin, a known position of biological importance ”. The study authors define the set of mutations detected in the rather peculiar English variant: “The B.1.1.7 lineage – they write in the research summary – carries a greater number of genetic changes than usual in the virus. The accumulation of 14 lineage-specific amino acid substitutions prior to detection is unprecedented, to date, in global genomic data for the COVID-19 pandemic virus.
What the experts say
While all of this information suggests that the English variant has higher transmissibility, as virologist Christian Drosten of the Charité University Hospital in Berlin pointed out to Science, it is premature to say that this is the case. “There are too many unknowns to say something like that,” specified the expert. Drosten gives the example of the Spanish variant B.1.177 detected this summer, which was also believed to have higher transmissibility, given the boom in cases detected in various regions. However, now it is no longer believed to be, and the German virologist claims that the rapid spread of the new variant may have been “determined by chance” and not by the mutations detected. Virologist Emma Hodcroft from the University of Basel also indicates that the data for the Spanish variant were, at first, “confused and distorted,” so we must proceed with great caution even for the English variant. Scientists at the University of KwaZulu Natal are less “optimistic” that they have identified another variant in Africa with N501Y mutation, which also seems “to spread much faster”, as specified in Science by virologist Tulio De Oliveira. According to Dr. John Nkengasong, director of the African Centers for Disease Control and Prevention, this variant can cause a More severe COVID-19 in youth, but even in this case “you need to get more data to be sure.” It should also be noted that for the study “Neutralizing antibodies drive spike-mediated evasion of SARS-CoV-2,” led by virologist Ravindra Gupta from the University of Cambridge, 69-70 deletion appeared together with another mutation called D796H on the virus from a patient who was hospitalized for months and then passed away. Undergoing laboratory testing, this virus was less sensitive to plasma than cured rich in antibodies compared to the original “wild” virus. Also in this case, the susceptibility to antibodies linked to the mutations identified in the English variant should be investigated thoroughly.
What to do to stop the English variant
In light of these premises, the ECDCs have listed some “tips” to stop the spread of the variant around the world. First, they recommend that all laboratory-isolated SARS-CoV-2 coronavirus samples be analyzed in a timely manner to “identify cases of the new variant,” thus activating the surveillance and related system. contact tracking. Second, they specify to use the PCR (polymerase chain reaction) as an indicator of new cases; finally, they ask to monitor vaccinated individuals to identify possible drug “failures”, sequence isolated viruses to determine their genetic characteristics and know what they are facing.
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