It was in December 2019 that the first cases of coronavirus were reported in a seafood market in Wuhan, China. Since then several speculations over its origin surfaced on the internet, and some conspiracy theorists even claimed that Covid-19 could be a bioweapon developed by China. However, a new study report claims that coronavirus might be circulating harmlessly among humans for many years.

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How did coronavirus turn deadly?

A study conducted by an international team of scientists that includes researchers from the United States, the United Kingdom and Australia found that the supposedly harmless coronavirus might have mutated, and have caused all the chaos which we see today.

"It is possible that a progenitor of SARS-CoV-2 jumped into humans, acquiring the genomic features described above through adaptation during undetected human-to-human transmission.

Once acquired, these adaptations would enable the pandemic to take off and produce a sufficiently large cluster of cases to trigger the surveillance system that detected it," wrote the researchers in the study report, now published in the journal Nature.

During the research, scientists analyzed genomic data and found that the receptor-binding domain of Covid-19 was so effective, that they must have evolved as such. This single factor suggests that this virus might have swept through humans for years, before turning deadly due to mutation in recent months.

Coronavirus is not a bioweapon

The new research report also rules out the possibility of coronavirus being a bioweapon developed by China. Experts also suggest that the new coronavirus might have reached humans from animals, and over the years, this pathogen might have acquired the ability to spread from humans to humans.

"The second scenario is that the new coronavirus crossed from animals into humans before it became capable of causing human disease. Then, as a result of gradual evolutionary changes over years or perhaps decades, the virus eventually gained the ability to spread from human-to-human and cause serious, often life-threatening disease," wrote Francis Collins, Director of the National Institute of Health in a recent blog.