Origin of SARS-CoV-2: The zoonosis theory remains the most supported

More than two years after the appearance of the first cases of COVID-19 in China, the origin of the SARS-CoV-2 virus has not yet been determined by the scientific community. This does not mark a path on the explanation of its emergence.

In early 2021 a team of international researchers conducted an investigation in China to collect evidence that could reveal how the virus was transmitted.

COVID-19 keeps the world in suspense for two years: its origin is still uncertain and there are multiple variants

The international team came up with four introductory scenarios. In an article published in Survival magazine last November, Gigi Kwik Gronvall, a senior researcher at the Johns Hopkins Center on Health Safety, outlines these theories as well as explaining what actions could be taken to support them. .

1. Animal origin

The immunologist by training points out that there are precedents in the natural appearance of this type of virus and remembers when SARS was spread in 2002 before the silence of the Chinese authorities. Precisely many of the cases were of people who worked in the markets and that the virus had spread in palm civets, whose meat was sold. By 2017 it was conclusively determined that the virus had come from bats.

In the international report, it was mentioned that the authorities confirmed that the animals that were sold in the Huanan market, in Wuhan, came from farms with licenses for reproduction and quarantine.

The author mentions that a study on severe tick-borne fever with thrombocytopenia syndrome documented animals that were assumed not to be on the market and that were not reported to the WHO, these were sold between 2017 and November 2019.

“Raccoon dogs, marmots, civets, minks, Siberian badgers, and many other furry mammals that could have served as intermediate hosts for the SARS-CoV-2 virus were sold openly, illegally, and profitably on the market. An intermediate animal origin for the virus could have been present in the markets, but as samples were not immediately taken, a conclusive determination may never be made about the role that animals in the markets played in triggering the pandemic. ”, Indicates the article.

It also mentions that although the genetic sequence of the virus in the first cases was not identical, it does constitute “additional scientific evidence of a natural emergency.”

These samples of the first known cases divided the A and B lineages in two, the second being the one that has spread the most in the world.

“Bat populations could be sampled to detect similar viruses. If China is not interested in conducting or facilitating such studies, perhaps the authorities in Indonesia and Cambodia, which also have bat colonies, can be persuaded to do so. Close relatives of SARS-CoV-2 have also been identified in bats in Laos. Blood banks that stored blood samples from November and December 2019 could be screened for earlier, perhaps asymptomatic, cases. This could provide information on the location of the infections and on the genetic sequence of the virus ”, it is added.

How did COVID-19 arise? Its origin remains a mystery

2. Origin in laboratory

Kwik indicates that in the first sequence some scientists were alarmed by the characteristics that it presented, which made them think that it had been created in a laboratory. He mentions that one of the characteristics that attracted attention was that of the furin cleavage site, which allows it to enter cells as well as that some base pairs of ribonucleic acid (RNA) seemed atypical, although this was refuted in April of 2020 in the journal Nature Medicine.

“Another factor that hinders support for the theory of a non-natural virus are the serious limitations in the ability to predict function from the genetic sequence … Designing a new virus to be pathogenic and transmissible may be beyond current scientific capabilities. However, it is possible to use the natural process of viral evolution to select a virus that could become more transmissible in a particular animal, or replicate in cells taken from an animal, “he added.

3. Origin by accident

It has also been mentioned that SARS-CoV-2 was released after an accident in a laboratory in China in workers. Given this, the immunologist has indicated that with the available evidence it is unlikely that this event was the cause of the pandemic.

“Accidents, of course, do happen, but when laboratory accidents have occurred, they have generally only affected the laboratory worker and sometimes close contacts. Although theoretically possible, no previous epidemic or pandemic has originated in a bio-research laboratory, ”it is said.

He also explains that several incidents have been poorly described in the media in reference to this issue.

In Wuhan there are two research institutions in which research on the coronavirus was carried out before the pandemic began.

“However, an accident scenario would be viable only if the SARS-CoV-2 virus (or something very similar) was in those labs. This has not yet been established for any of the laboratories. Without perfect knowledge of the first cases of SARS-CoV-2, it is impossible to completely rule out the origin of the virus in a laboratory accident. But especially if it was a naturally evolved virus, some additional information suggests that a laboratory accident is not a likely scenario, “he added.

The researcher points out that knowing how SARS-CoV-2 managed to affect humans will prevent future pandemics, but that this will take many years and that the population will have to live with that uncertainty. (I)