Delta variant, what we know about its new mutation and why (for now) it doesn’t have to worry us

Again, in the absence of confirmation, a Covid variant is used to cover other problems. In truth, we are not even talking about a “new variant”, but a sub-variant of the Delta, namely the AY.4.2 lineage. Thus all by-products of the new Coronavirus mutant from India were also named Delta plus. In a previous article last June we had dealt with, for example, the AY.1 lineage. The “new” sub-variant emerged a month later.

Can AY.4.2 alone lead to a significant increase in infections?

Someone could blame the sub-variant for the boom in British and Russian cases. Instead, it is necessary to reflect on other concomitant factors, combined with the fact that Delta was already worrying in itself and that vaccinations (introduced very early by the British) significantly lose their effectiveness in mild forms within five or six months. So let’s add the general laxity in Russia and the easing of containment measures in the UK. At the moment there are nine known cases in our country identified between September and October. In Israel there would be six in all. We take into account that the genetic traces of AY.4.2 represent 10% of cases worldwide, in fact almost all in the United Kingdom: 21,000 out of 22,000 globally.

Too early to panic

The first to invoke caution is the geneticist of the University of Trieste Marco Gerdol in a recent post on Facebook. Recent more accurate estimates speak of a transmissibility of the sub-variant increased by about 10%. For the reasons just introduced, we have no way of considering this inherent property of mutated SARS-CoV-2. If we have to talk about a greater danger, this should be evaluated relative to the generally known one of the Delta variant considered YOU (of greatest concern). For more information on how variants are classified, we suggest reading our previous article. On the other hand, the more time passes, the greater the mutations affecting the subunit S1 of the RBD (Receptor Binding Domain) of the Spike protein, or, simplifying, that portion of antigen that allows the virus to bind to cells to infect them.

The main mutations of AY.4.2

Every mutation in the genome that affects the Spike protein is monitored and studied. Those associated with a greater ability of the virus to be infectious or evade the immune defenses, are for example E484K and N501Y. In the case of this sub-variant they appear of particular interest A222V e Y145H. The first does not seem at the moment to give worrying results, both from the point of view of transmissibility and response to antibodies; we find it, for example, also in other Delta sub-variants that result in decline. The second is present in other variants – such as Alpha and Mu – and could theoretically induce, given the kind of modifications to the Spike it involves, a greater evasion of the immune defenses.

First tracks also in the United States

In the United States, where the sub-variant begins to be isolated, it corresponds to less than 0.05% of sequences. According to the CDC “There is no evidence that sub-line AY4.2 affects the effectiveness of our current vaccines or therapies,” as reported Business Insider.

Professor Francois Balloux, professor of computational systems biology and director of the UCL Genetics Institute, he said in an October 19 interview for Science Media Centre, that regarding the case boom in the UK ‘AY.4.2 still has a rather low frequency, a 10% increase in its transmissibility may have caused only a small number of additional cases’.

According to the Professor, we have had far more worrying variants. “As such, it did not drive the recent increase in the number of cases – continues Balloux – this is not a situation comparable to the emergence of Alpha and Delta which were much more transmissible (50% or more) than any strain in circulation at the epoch. Here we are dealing with a potential small increase in transmissibility that would not have a comparable impact on the pandemic. ‘

Cover photo: Alexandra_Koch | Stock image.

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