A new strain or subline of “Omicron” – BA.2 – began to conquer the planet. “Champions” were Denmark and the Philippines, where the first version of “Omicron” – BA.1 was replaced by a new one in less than a month and the wave of coronavirus that had subsided resumed. Next in line, according to epidemiologists, are Sweden, India, South Africa … We talked about a new misfortune with immunologist Nikolai Kryuchkov.
– Nikolai Alexandrovich, tell us what kind of new version of Omicron is this? Why do scientists associate the increase in the incidence in Denmark with BA.2?
– In the process of evolution of coronavirus infection, descendants are separated from predecessors, strains and lines of ancestors. It’s like more or less large branches appear from the trunk of a tree. There are a lot of them, but scientists pay attention only to “super mounts”, for example, “Omicron”. It certainly stands out for serious features – clinical, epidemic.
When Omicron appeared, it was found to be highly contagious, a large number of mutations, avoiding specific immunity, reduced pathogenicity and low mortality. Further evolution does not stop: a large number of infections gives rise to the emergence of an increasing number of mutations, and some certain super strains periodically “shoot out” among them.
– So BA.2 is a strain?
– The Omicron line is a collection of strains with certain common features, mutations, but they are not identical. And now a new strain appeared inside the line – BA.2. Its differences from the “ancestor” are small, but there are facts that cause concern.
In some countries, like Denmark, this variant is already beginning to crowd out other strains of Omicron, including, of course, the most contagious BA.1 until a certain time … First, a wave of mixed Omicron from BA.1. and VA.2. led to a decline in the incidence – the Danes, who fell ill at 3.5 thousand per 1 million a day, believed that they definitely had a fracture, because there was nowhere to grow Omicron further (data from the USA and Britain showed an increase to 2600 infections per million , and then there was a decline to 1300).
But the Danes did not guess – very quickly, within a week, the coronavirus began to grow again, there are already up to 5 thousand cases per 1 million per day. And this is associated precisely with the period of replacement of other strains of the line by strain BA.2.
– It turns out that it is more contagious and, accordingly, has more mutations in the spike protein?
– She has few differences from BA.1. But it turns out that they are enough for the BA.2 to look the most effective and strong among all the Omicrons.
– Has there been an increase in diseases in the UK, where Prime Minister Boris Johnson recently announced the cancellation of some anti-epidemic measures?
– Yes, growth is also detected there.
– Is it possible to say where the evolution of Omicron will go next?
– At least, it is clear where this VA.2 came from – from Omicron, but where Omicron itself came from is not yet very clear. All we know now is that he is not a descendant of Delta. By the way, “Delta” should not be discounted either. Despite the more contagious nature of “Omicron”, it can survive in the population in certain quantities and then surprise us.
Studies on mice have shown that those who have just been ill with Omicron receive weak immunity to other lines of coronavirus, in particular, to Delta. This is such a swing – first one line and its descendants come to the fore, then others. To be honest, I used to think that we would face a super-Delta, but it turned out differently. Now, when over time our immunity will be actively developed at Omicron, another super-descendant from another line will appear.
– Yes, what is it! This will never end!? After all, the pathogenicity of “Omicron” is falling. Everyone is talking about it…
– Of course, the situation is not hopeless – pathogenicity due to high contagiousness should fall, the consequences of the pandemic will decrease. But at first, despite the decrease in the lethality of the disease, mortality from it can grow due to a very large increase in infection.
– Does a person who has not previously been ill with coronavirus become more protected after Omicron?
– He may be more prone to, for example, “Delta”.
– Why didn’t a new subline of coronavirus appear in our country first?
– We have a kind of time lags with Europe. There are large transport hubs, which attract a lot of people from different countries. We are far from those streams, we have fewer airports, and our population density is much lower.
– How long will there be an increase in the incidence in Russia?
– I think, another 3-4 weeks, until it reaches 100 thousand infected per day, then there will be a decline – to about 30 thousand per day, and after some time – closer to April, a new rise will begin already against the background of BA.2.
Source From: MK