Discovered a few weeks ago in South Africa, Omicron is a new variant of SARS-CoV-2 which worries scientists. They are mobilizing around the world to learn about its mode of transmission and its potential for resistance to vaccines.
Photo credit: Futura-Sciences
However, researchers still cannot determine the origin of this variant and therefore cannot assess the threat in the short term.
Hypotheses on the formation of the Omicron variant
Analysis of the genetic code of the Omicron revealed that it is formed from sequences of the virus discovered in mid-2020. This assumes that its original version did exist over a year ago. It would therefore have had enough time to develop to reach this current stage. In view of this remark, three kinds of hypotheses are put forward by scientists on the formation and development of Omicron.
Hypothesis 1: Omicron comes from an animal source
The mid-2020 strain of the virus may have infected an animal population, scientists say. It would then have evolved and would have spread in this environment before being reinjected into a healthy person.
However, Trevor Bedford, a computational virologist, gives little credit to this hypothesis since it “becomes technical”. If this were verified, he estimates that there would be in the genetic material of Omicron, an animal strain. However, scientists have instead found a human RNA, which leads to the conclusion that it evolved in a human.
Hypothesis 2: Omicron developed in cryptic mode
The second hypothesis formulated suggests that the mid-2020 strain of the virus has grown in an area without medical surveillance. The scientist Bedford strongly suspects southern Africa where the current sampling of the coronavirus is less numerous.
This would have allowed it to develop all this time and thus acquire the most mutations until its appearance. However, this hypothesis is also ruled out since it could have started to spread a little earlier. It would therefore have drawn the attention of countries with very efficient health surveillance systems.
Hypothesis 3: Omicron developed in an immunocompromised
The other hypothesis that interests scientists is that the virus could have been incubated in an AIDS patient not undergoing treatment. Although it cannot be eliminated, the body of such a person is sufficiently equipped to survive the contamination.
Thus, the strain in mid-2020 may develop new, more complex mutations with each replication. In this case, the strain has therefore spread to other organisms from the person incubating it. That said, it is questionable why this diffusion did not occur at a stage of mutation prior to Omicron.
Why are researchers interested in the origin of the Omicron?
Determining the origin of the Omicron as quickly as possible is a real challenge for scientists. This could, in effect, help them to assess the level of potential dangerousness of the threat.
As an indication, note that if the strain had evolved in a large population, the virus might not be contagious enough. On the other hand, in the event that it would have developed in the body of an immunocompromised person, the rate of transmission would be greater. Given the current health context, researchers are focusing more on this last hypothesis.