Did Omicron variant of COVID-19 evolve in rats?

A new variant of COVID-19 was first reported to the World Health Organization (WHO) from South Africa on November 25. On November 26, the WHO named the new variant detected in South Africa, as `Omicron`. The WHO has classified Omicron as a `variant of concern`. Dozens of countries have imposed travel restrictions on the southern African nations since the mutation was discovered. However, a theory has emerged, claiming that the variant originated from rodents.

As per some scientists, the omicron variant of COVID-19 may have evolved in a nonhuman animal species, potentially a rodent.

According to a report by STAT news, some scientists speculate that some type of animal, potentially rodents, were infected with the SARS-CoV-2 virus, popularly known as COVID-19 or coronavirus, sometime in the mid-2020. The virus evolved in the species, accumulating around 50 mutations on the spike protein before infecting the humans. 

The process of an animal pathogen infecting humans is called a zoonotic event while a reverse zoonosis is when such pathogen passes back to the animal. As per the report, Kristian Andersen, an immunologist at the Scripps Research Institute, has been raising the idea that Omicron may have emerged from a reverse zoonotic event.

Andersen says that the Omicron variant is formed after mutations of several variants so it is quite possible that it has gone through the process of reverse zoonosis. Some scientists also argue that in a person with weak immunity, the coronavirus might have mutated itself to develop new variants. However, there isn't enough evidence to prove this

Another expert, Robert Gary, a professor of microbiology and immunology at Tulane Medical School, says that Omicron has 7 out of 32 mutations that can infect rodents. Whereas, there were only seven mutations in the first variant alpha of the coronavirus. However, Gary is still in a dilemma about whether the Omicron variant originated from animals or evolved into humans.

The Omicron variant has a gene that infects mice. This has been confirmed. Because the number of mutations that have been seen in this variant have not been witnessed in any other variant of the virus so far. That's why scientists are also looking at it from the point of view that it may have developed in rodents.

Evolutionary biologist Mike Voroby of the University of Arizona says that this is a very surprising variant because if this variant can infect an organism outside with chronic disease, wonder what it can to humans. Due to this, there is also the possibility of many more dangerous variants emerging. Although Mike is not ready to accept the fact that it has come out of a rodent, he believes that it has developed in the body of a person with a weak immune system.

According to another theory doing the rounds regarding the origin of Omicron, a person with a weak immune system must have been infected by a variant of the coronavirus. At the same time, he must have also had some kind of chronic infection, due to which, the coronavirus in the body slowly kept changing its form. That is, it kept mutating. It has mutated so much that it has emerged as the dreaded Omicron variant.

On the other hand, virologist Christian Drosten of Charité University Hospital in Berlin denies both these theories. He says that Omicron may have first appeared in a population with weak viral surveillance. It must have developed there and the infection must have been spreading. But no one noticed this variant. Drosten thinks that this virus did not even originate in South Africa because there was a lot of genome sequencing going on there. Instead, it must have developed in some remote southern region of South Africa during the winter season.