The weekend science ticket with like every weekend Mathilde Fontez, editor-in-chief ofEpsiloon. Today, we are talking about Omicron, the new variant of SARS-CoV-2 which has worried the planet a lot in recent weeks.
franceinfo: He is very different from the others, which raises the question of his origin …
Yes, that is the question of the moment. So it is of course less urgent than knowing how this new variant will modify the pandemic, how dangerous and contagious it is. But it is an important question. Because by understanding how Omicron emerged, we will be able to predict what will happen next, the arrival of variants afterwards.
And what is questioning is that Omicron is very different?
He has a lot of mutations. Fifty. 32 of which just from the Spike protein, you know this spike protein that the virus grabs hold of cells in the human body. And many of these mutations had never been seen in other variants.
Which makes researchers say that it did not develop from the Delta variant. In fact, they are struggling so far to pin down his closest relative. One of the hypotheses is that it would be a strain that diverged very early from the original virus, possibly as early as mid-2020.
This variant would have evolved in its corner?
That’s it. To reach such a level of differences compared to the original SARS-CoV-2, and to the variants that we have seen so far, a great evolutionary pressure is needed which selects these mutations. Which means time. The virus must have evolved in the dark, somewhere. And we discover it today, very different from the others.
So where did he hide to evolve? There is no answer at this time. Only hypotheses. Three in fact. Either it has evolved in a particular population, which has not been tested. Probably not in South Africa – that’s where it first came to light, but testing is common there. The second hypothesis, the most likely for some of the specialists, is that it evolved in immunocompromised people, and who therefore harbored the virus for months. For example people with HIV.
And the third hypothesis?
It is more speculative, and perhaps more worrying if it were true: it is the idea that the virus would have passed back to animals. Since the start of the pandemic, some specialists have been worried about this: could animal populations constitute a kind of reservoir of the virus, likely to make it reemerge in humans, even after it is gone? cleared?
There is this example of deer in Iowa, which were tested between November 2020 and January 2021: 80% of them were carriers of the virus. Omicron could have circulated and evolved in an animal population, then passed back to humans. To decide between these three hypotheses, and to draw lessons, we will have to wait for the data.