INTERVIEW – Origins of Covid-19: “All the data converges towards wild animals”

The origin of Covid-19 at the heart of a new study. Nearly five years ago, in 2019, a new virus emerged in China and was about to spread around the world, killing millions and causing immense economic and social damage across the planet.

But what was the origin? Animals such as pangolins or bats, as suggested in 2020? A laboratory leak, a hypothesis taken seriously, particularly in the United States? In work published this Thursday, September 19 by the journal Cellscientists finally lift the veil on the transmission of the virus to humans. Florence Débarre, CNRS researcher at the Institute of Ecology and Environmental Sciences, who coordinated this study with a large international collaboration, details the results to TF1info.

The possible origin of Covid-19 has been the subject of much speculation and speculation. How did you go about conducting the study that is intended to determine it?

Florence Débarre: The origin of the data used in our work dates back to 2020, just after the closure of the Huanan market in Wuhan (China), where the first cases of Covid-19 were detected. Teams from the Chinese Center for Disease Control were dispatched to the site and took samples from surfaces in the market: floors, walls, cages, gloves, etc. The samples were analyzed by PCR to look for the presence of the virus, and were sequenced to identify all living species present in the sample.

The hypothesis of a laboratory leak deserves to be considered

Florence Debarre

What do the analyses reveal?

In some samples, both genetic traces of animals and the virus were detected. Of course, with our data, it is not possible to demonstrate that the animals themselves were infected, but the results of the analyses correspond to what we would expect to see if animals were infected. This work therefore confirms that at the Wuhan market, at the end of 2019, wild animals were indeed on sale. Some of these animals belonged to species already implicated in the emergence of severe acute respiratory syndrome (SARS) in 2002. They were located in the southwest part of the market, which also happens to be a hotspot for the spread of the virus among humans.

Which animals are affected?

The species identified include raccoon dogs and civets (a distant cousin of the cat, editor’s note). They may have transmitted the virus to humans. For raccoon dogs, experimental infections have already shown that these animals can transmit the virus between themselves.

You don’t quote the pangolin Or the batanimals that were mentioned in 2020 to find the origin of the pandemic. How can this be explained?

With the data we have, we only have access to the last steps, and not what happened before. But the virus must have come from somewhere when it arrived at the market. There may have been a long chain of transmission that could have started, for example, in a bat population in southern China. Perhaps other animal species were also involved, including pangolins. As for the distant origin of the virus, nothing can be ruled out.

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Do these works put an end to the laboratory leak hypothesisconsidered serious, especially in the United States?

There is no definitive answer. The hypothesis of a laboratory leak is worth considering: the first cases of Covid-19 were detected in a city with a large research center working on bat coronaviruses. This coincidence necessarily requires taking this hypothesis seriously. That said, all the data currently available converge on a natural origin linked to wild animals at the Huanan market.

Why is it important to find the animals causing the pandemic?

The origin of the virus is a big question we have left from this pandemic. Working on the subject exposes us to attacks and harassment. But beyond the historical motivation that is my own, it is necessary to understand to help prevent future epidemics. This work confirms that bringing live wild animals that could potentially carry viruses into dense urban centers is really not a good idea. This does not mean that the next pandemic will have the same type of origin, but we at least know these risks.