CORONAVIRUS – The denial of the director of the P4 laboratory of the Wuhan Institute of Virology, Shi Zhengli is once again categorical: “How the hell can I provide proof of something that there is no proof of?”. The one nicknamed “batwoman” for her work on bats thus expressed herself on June 14 in theNew York Times to refute the theory that the virus that caused Covid-19 could have escaped from his laboratory.

Certain pressure has undoubtedly pushed one of the officials of the Wuhan Institute of Virology (WIV) to come out of her silence to defend the reputation of her institution. In recent weeks, the debate on the origin of the coronavirus has been revived in the media: the laboratory accident is increasingly mentioned as a possible trigger for the pandemic.

The question is not clear: if some researchers are to seriously investigate the track of an accidental leak of the coronavirus from a laboratory, the majority of scientists still favor the track of zoonosis, that is to say that of transmission of the disease from animals to humans.

A leaden cover on the scientific debate

The contradictory debate on the origins of the coronavirus has not always been easy. It was indeed difficult for a long time to discuss the hypothesis of the laboratory accident, especially after the publication by the Lancet in February 2020 from a letter signed by 27 experts qualifying as a conspiracy theory any hypothesis suggesting that the Covid could have an unnatural origin. Such a position taken in a leading scientific journal had the consequence of “putting a leaden cover and sealing the debate by treating any researcher who expressed doubts as a conspirator” laments the epidemiologist Antoine Flahault contacted by TheHuffpost.

However, it later turned out that a significant conflict of interest existed for one of the main instigators of the letter from Lancet, epidemiologist Peter Daszak. The association he chairs, Eco Health Alliance, has been funding research on bat coronaviruses at the WIV for more than five years. As a result, the researcher had to withdraw on June 22 from the commission of inquiry launched by the Lancet on the origins of the Covid.

The political context of the time with Donald Trump’s desire to point out the responsibility of China and to qualify the virus as “Chinese” to favor the hypothesis of the laboratory accident also weighed, explains to the Huffpost Vincent Maréchal, professor of virology at Sorbonne University. “At that time, it was scary to be associated with Trump and to be exploited by racists, therefore people no longer wanted to publicly demand an investigation of the lab’s thesis,” biologist Alina Chan told New Zealand Herald.

With the consequence of greater difficulties, according to some researchers, to publish articles in scientific journals about the laboratory accident. The Lancet thus refused to publish a letter asking not to rule out the hypothesis of a leak, revealed to the Huffpost José Halloy, professor of physics at the University of Paris and co-signer of the forum with a group of thirteen other experts.

For this article, The Huffpost tried to contact several research institutes. The Institut Pasteur was unable to respond to our requests by citing a lack of availability of its researchers and Inserm declared that its experts did not wish to speak for the moment on the question of the origins of the coronavirus because of its political character.

The return to favor of a laboratory leak

The scientific debate on the origins of the coronavirus has recently been turned upside down by new political and scientific events. First, on March 30, the boss of the WHO, Tedros Adhanom Ghebreyesus makes a statement to request a new investigation into the hypothesis of a leak of the virus from a laboratory in China to explain the origin of the pandemic of Covid-19.

Then the election of Joe Biden relaxes the political climate. With the new president commissioning his own investigation into the coronavirus from his services, it becomes possible to work on the laboratory accident without being accused of playing Trump’s game. On May 13, 2021, an opinion piece of 18 scientists is published in the journal Science calling for an investigation into the origin of the coronavirus whether natural or stemming from a laboratory accident.

Another element that prompts some researchers to consider a laboratory leak, the fact that nearly a year and a half after the start of the pandemic, no zoonotic intermediary has been found despite the collection of 80,000 samples from animals in China.

“The absence of proof is not proof, this does not mean that the epidemic is not a zoonosis”, explains to the Huffpost Étienne Decroly director of research at the CNRS at the University of Aix-Marseille in Marseille and signatory of the letter sent to Lancet calling not to neglect the trail of the laboratory accident. “This still calls into question the mechanism of emergence, because at this level of sampling, one would expect to identify the intermediate host.”

Two scenarios for an accident

How then could a laboratory accident have taken place? Scientists put forward two different scenarios.

First, the accidental leak of a virus that exists in its natural state and stored within the WIV. “One of the official vocations of the Wuhan laboratories is to host research projects on how coronaviruses emerge from natural reservoirs” specifies Vincent Maréchal. Gold according to Antoine Flahault “lSecurity protocols have not been strictly observed ”at WIV, a risk revealed in 2018 by diplomats from the United States Embassy in Beijing.

Therefore a possible scenario of the origin of the epidemic would be that of the contamination of a WIV researcher by a virus still unknown to the scientific community. “All viruses stored in freezers the Wuhan Institute of Virology are not declared” explains to Huffpost Alexandre Hassanin, researcher at the National Museum of Natural History (MNHN) and specialist in bats.

“If you take the example of the RatG13 coronavirus, which was the subject of a publication this year by the WIV, it was collected in 2015. Scientists take the necessary time to research before making their publication which can take years ”, adds the researcher. The Wall Street Journal claims that several lab technicians fell ill in November 2020, a claim since denied by the Chinese Foreign Ministry. In addition, dEpidemics have already been triggered in the past by laboratory accidents, such as the H1N1 in 1977 recalls Antoine Flahault.

The other scenario linked to a laboratory accident involves the artificial creation or manipulation of a virus. In this hypothesis, a particularity of Sars-Cov2 which makes the virus particularly contagious for humans, the “furin cleavage site”, is pointed out by certain researchers.

“Proponents of the origin by the laboratory accident, argue that it is known that coronaviruses have difficulty crossing the barrier of the species and that in other laboratories, cleavage sites have been added to understand the mechanisms of crossing of the species – within the framework of manipulations known as gain of function -, advances Étienne Decroly: ”They believe that this site was added to the progenitor of Sars-cov 2. ”

Is zoonosis more likely?

If the hypothesis of the laboratory accident is now considered a serious avenue, it does not seem to be the one favored by the majority of the scientific community.

In the first place, because another hypothesis, zoonosis, that is to say the transmission of the coronavirus from humans to animals, is considered by many scientists to be more likely. “The natural hypothesis is reasonable enough so that we do not need to find an anthropogenic origin, that is to say an intervention by the hand of man, to explain the pandemic”, judge Vincent Maréchal.

“A year ago, when Sars-cov 2 emerged, this was the main hypothesis that was raised by scientists, because we know that these are mechanisms that allow the emergence of a virus in the population, as for the MERS, Sars-cov1 of 2003 ”, points out Étienne Decroly.

“The scenario of intermediate host contamination remains an important hypothesis supported by the data as well,” says Alexandre Hassanin. “We know that pangolins have carried two coronaviruses close to Sars-cov 2 in two regions of China. And nearly a million pangolins
have been imported into China in a decade as part of illegal trafficking. ”

Second, the arguments put forward to justify an artificial origin of the coronavirus are the subject of controversy. “There is no interest for Chinese researchers to artificially modify Sars-cov 2. What would be their interest in carrying out such work on an unknown virus?”, Considers Alexandre Hassanin.

The presence of the furin site, put forward as proof of an artificial manipulation, can also be taken up in the arguments of the supporters of the natural origin. “We know that Sars-cov 1 does not have a furin site but also that other coronaviruses do, such as MERS. The same observation is therefore seen under different hypotheses. There are no tangible facts to rule out one hypothesis compared to the other ”, admits Étienne Decroly.

Will new data advance the debate?

Faced with the ambivalence of the arguments invoked, how could the scientific debate advance? “For us scientists, the position is simple: science must come back to the heart of this question, we must have access to samples in a total and freest way possible in order to collect new elements to document the one or the other of the hypotheses ”, claims Étienne Decroly.

And new clues could come from outside of China. “The accumulation of data will be able to provide strong enough arguments to determine the geographical origin of the coronavirus. This is to collect data outside of China on the coronaviruses present in South East Asia. If we see that these coronaviruses are more divergent than those found in Yunnan, this will clearly mean that the Covid at the origin of the epidemic comes from Yunnan ”, postulates Alexandre Hassanin.

Which, according to the researcher, would also make it possible to reconstruct the path taken by the coronavirus. If the virus does come from Yunnan where WIV scientists take coronavirus samples, ″ the most likely scenario to determine the origin of the coronavirus is to consider that these viruses have been brought back to Wuhan by researchers. ”

Alexandre Hassanin is also working on a forthcoming publication whose data would suggest that Sars-cov 2 would have been transmitted to humans without an intermediate host. A hypothesis which, if confirmed, according to the researcher could tip the scales a little more towards the laboratory accident.

“For there to be contamination that crosses the species barrier, the individual must be confronted with fairly high concentrations. In the absence of an intermediate host, this can only happen in the laboratory, where the viruses are cultured and there for the moment there can be a contamination which would not take place in nature ”, deduced from this. the searcher.

In parallel, other researchers have also launched new investigations on the question of the intermediate host, but to prove its existence. This is the case of the German virologist Christian Drosten for whom possible hosts would be fur animals such as raccoon dogs whose trade and breeding in China were already at the origin of the Sars epidemic in 2003.

The debate on the origins of the coronavirus therefore remains open, but less conjectural avenues, because this time based on new tangible data, seem to be emerging.

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