As research to determine the origin of Covid-19 continues, the theory of the laboratory accident is making a comeback in the American debate.

On Sunday, claiming to be based on a US intelligence report, the "Wall Street Journal" claimed that three researchers in Wuhan had been affected by November 2019 with "symptoms compatible with those of Covid-19".  

Long brushed aside by most experts, deemed highly improbable if not far-fetched, the theory of the laboratory accident to explain the origin of Covid-19 has come back in force in recent weeks in the American debate.

The animal "intermediate host" has not yet been discovered

"The list of people supporting the thesis of an animal origin has not moved. And that of people suggesting that (the virus) may have come out of a laboratory continued to grow," Scott summed up Monday on CNBC Gottlieb, a respected former boss of the United States Drugs Agency (FDA).

"A year ago," supporting the thesis of a natural origin "made a lot of sense because it was the most likely scenario," he explained.

But what is called "the intermediate host", that is, the animal from which the virus was transmitted to humans, has still not been discovered.

"And it's not for lack of looking."

>> LIVE -

Coronavirus - follow the evolution of the situation Tuesday, May 25

“The question, for many people, is, when do the coincidences get too many?” He asked, pointing to the growing body of “circumstantial evidence”. 

Wuhan researchers sick from November 2019?

On Sunday, the

Wall Street Journal

claimed to have had access to unpublished information from American intelligence, reporting that three researchers from the Institute of Virology in Wuhan, China, had suffered as early as November 2019 from "symptoms compatible with both those of Covid-19 and a seasonal infection ", requiring hospital treatment.

Beijing has denied the

Wall Street Journal information

, calling it "totally false". 

"We have to get to the bottom of it, whatever the answer, and it is a priority for us", hammered Monday Andy Slavitt, adviser to the White House for the fight against the Covid-19.

"We need a completely transparent process from China, and the WHO to help on this."

China's lack of transparency criticized

After a four-week stay in Wuhan earlier this year, a joint study by experts from the World Health Organization (WHO) and China ruled in March "extremely unlikely" a laboratory accident.

But the boss of the WHO himself, Tedros Adhanom Ghebreyesus, had called for a new investigation into the hypothesis of the laboratory leak.

Several countries, including the United States, had expressed their "concerns" and called on China to give "full access" to its data.

A request renewed on Monday on the occasion of the 74th World Health Assembly. 

"Need more research"

And calls for further investigation are growing, including within the scientific community.

In mid-May, around fifteen experts published an article in the prestigious journal Science: "We need more research to determine the origin of the pandemic", they claimed.

Theories of animal or accidental laboratory origin "both remain viable", they wrote, but "they have not been given fair consideration."

CORONAVIRUS ESSENTIALS

> Reopening of terraces: what risk of Covid contamination outdoors?

> "I'm afraid ...": the cabin syndrome, or the fear of resuming a normal life

> Covid: the countries which have done the opposite of us "have been better on all fronts"

> Coronavirus: why can a PCR test be positive one month after infection?

> Reopening of the terraces: how to indulge yourself while eating a balanced diet

Both hypotheses "must be seriously considered until we have enough data," they said, asking "public health agencies and research laboratories to open their data to the public." 

In the United States, the hypothesis of a leak of the virus from the Chinese laboratory had so far mainly been fueled by the administration of Donald Trump.

"Now everyone recognizes that I was right when I declared Wuhan very early on as the source of Covid-19," the former US president triumphed in a statement on Monday.

"To me it was obvious from the start."

Experts remain cautious

However, many experts remain more cautious.

"Many of us think it is more likely that it is a natural event (...) but we do not have a 100% answer to this question," Anthony Fauci said on Tuesday. , eminent immunologist and adviser to the White House.

"We are all convinced that we should continue the investigation," he added.

But for Scott Gottlieb, the answer is likely to never appear clearly: "Assuming that (the virus) did indeed come out of a Chinese lab - and I'm not saying it did - we will never know without a whistleblower or regime change in China, "he said.