Two studies published this Tuesday in the prestigious journal Sciences conclude that the Covid-19 pandemic began in the market in the city of Wuhan, China, thus pointing to a very likely animal origin of the virus.
The first study is a geographical analysis that shows that the first cases detected in December 2019 were concentrated in the market. The second is a genomic analysis of the virus from the earliest cases, showing that the virus is highly unlikely to have circulated widely in humans before November 2019.
“It is important to understand that there are possible scenarios”
One of the authors of these studies, Michael Worobey, a virologist at the University of Arizona, had signed a letter in 2021 asking that the hypothesis of a leak from a laboratory in Wuhan be seriously considered.
But the data analyzed since then “has made it evolve, to the point that today I also don’t think it’s plausible that the virus was introduced in any other way than through the animal trade in the Wuhan market,” he said. a press conference. .
Kristian Andersen, from The Scripps Research Institute and also a co-author of these studies, said: “Have we disproved the lab leak theory? No. Can we ever? No. But I think it’s important to understand that there are possible scenarios and others probable. And that of possible does not mean equally probable”.
The animal that would have acted as an intermediary has not been identified.
The first study analyzed the places of residence of the first 155 cases identified in December 2019. The researchers showed that these cases were concentrated around the Wuhan market, unlike those registered in the following months, which coincided with neighborhoods of high density, showing the spread of the virus.
In addition, among the cases studied, people not directly linked to the market lived closer to it than those who worked in it or had recently visited it. This indicates that they were probably infected by their proximity to this place.
The researchers also analyzed samples taken from the market in January 2020, for example from a cage or carts. Their analyzes show that the samples positive for Sars-Cov-2 were concentrated in the southwest of the market, precisely where live animals were sold (including raccoon dogs, a species of badger, foxes, etc.). The animal that would have acted as an intermediary between bats, carriers of the coronavirus, and humans has not been identified.
important to understand
The second study is based on the analysis of the genome of the virus that infected these first cases. She concludes that two lineages of the virus, A and B, existed prior to February 2020. And that these two lineages were likely the result of two separate human transmission events, both in the Wuhan market.
Going forward, scientists stress that it is important to understand where the animals sold in the Wuhan market come from, to minimize future risks. So if gray areas remain, the researchers pointed out that the available information about the beginnings of this pandemic was, in fact, very detailed.
“There is this widespread feeling that there is no information that can tell us anything about the origin of the Covid-19 pandemic,” Kristian Andersen commented. “That is wrong.”
China has regularly been accused of withholding information or not fully cooperating with international investigations. Understanding how this pandemic started is crucial to help prevent future similar events and potentially save millions of lives. “Pandemics do not require us to appoint a responsible party, but they do require us to understand them,” Kristian Andersen concluded.
Source: BFM TV
