This is how the WHO investigates the origin of the coronavirus without ruling out the laboratory leak

• Research The 200,000 Chinese blood samples that 'hide' the origin of the coronavirus pandemic

• China Covid-19, a year later a WHO team arrives in Wuhan to investigate the origin of the pandemic

After two and a half years, with more than 530 million infections and six million deaths,

began to spread and how it came about

.

The scientific community was craving answers from a team made up of

who were recruited by the WHO late last year to try to decipher the origins of SARS-CoV-2.

That team, baptized as the Scientific Advisory Group for the Origins of New Pathogens, reduced by its acronym in English as

, has spent eight silent months, until on Thursday it published a

that appear in a dossier written by the first WHO team that traveled to

in February 2021 , the one designated as the epicenter of the pandemic.

The prevailing bet is the zoonotic origin and

to be the original hosts of SARS-CoV-2, but

before the coronavirus was transmitted to humans.

It is not even clear when it began to spread or from where.

Could it be a leak in the maximum security laboratory in Wuhan where they worked with dangerous pathogens that are cousins ​​of the current coronavirus?

The researchers do not close the door on this theory but, for now, as the latest report highlights, there is no new data to support that the virus escaped from the laboratory.

"The strongest evidence remains zoonotic transmission," said Marietjie Venter, WHO team leader and a virologist at the University of Pretoria in South Africa.

She was in charge of presenting the 46-page report.

"However, the precursor viruses that have been identified in bats are definitely not close enough to be the virus that spread to humans," Venter said.

The coronaviruses found in horseshoe bats in southern China, which are the same ones that were being studied at the Wuhan Institute of Virology, have a

, something that for scientists supposes a significant evolutionary distance, enough to lead to suspect that there was an intermediate carrier before passing to humans.

Venter wanted to clarify that the WHO group's report is based only on preliminary findings because the researchers "have not conducted their own studies, but have reviewed existing research."

In other words, Thursday's presentation does not resolve any of the doubts in the mystery, nor does it provide substantial data that the international community was not aware of.

The SAGO team appeared in October 2021, a few days after the Chinese authorities announced that they were going to analyze blood donations made during 2019 in Wuhan, collected at the city's Blood Center, where there are around 200,000 samples, marked by date and location, that could contain crucial signs of the first antibodies that would help determine how, when and where the Covid first crossed into humans.

Experts from around the world, including those at the WHO,

.

Indeed, one of the few new contributions to the report comes from Chinese researchers who are also part of SAGO: they provide data on blood samples taken from 40,000 people in Wuhan before the first official cases of Covid-19 emerged in December 2019. .

"Although 200 tested positive for SARS-CoV-2 antibodies, those antibodies failed to neutralize the virus in a confirmatory test, suggesting they were false positives," reads the report, which recommends

and also review pharmacy records between September and December 2019 to see if there are any unusual purchasing patterns that provide signs of early clusters of cases.

The problem, if one reads between the lines of some of the SAGO experts' claims, is that the published research suffers from some of the same limitations as the report that the WHO and China jointly presented last year.

In private, officials of the international body complain about the limits on collaboration that are often set by their Chinese colleagues.

because, in the words of an official from the Chinese National Health Commission, Western researchers are "infected by the political war against China.

According to the SAGO document, WHO Director-General Tedros Adhanom Ghebreyesus sent letters to Chinese Premier Li Keqiang and Health Minister Ma Xiaowei on February 14 and 21, respectively, requesting information on " a variety of factors," including hypotheses of a laboratory leak.

He has not revealed whether his letters received a response from the Asian country.

"All hypotheses must remain on the table until we have evidence that allows us to rule out or accept certain hypotheses," Ghebreyesus said Thursday.

"This makes it all the more urgent that this scientific work be kept separate from politics," he said.

The WHO leader knows that moving politics away from research is going to be an impossible task as long as Beijing continues to oppose further research into whether the virus could have leaked from the Wuhan Institute of Virology.

It also doesn't help that Chinese officials each month revive theories that the coronavirus could have reached China through frozen food or that the real source is a laboratory in the United States.

between Chinese and international experts.

The SAGO report concludes by recommending a close examination of the environmental samples taken from the Huanan market, indicated as a possible ground zero for infections, as well as carrying out "investigations and audits" on the farms that sent animals susceptible to SARS-CoV-2 to the market. .

A few months ago, a team led by Michael Worobey, an evolutionary biologist at the University of Arizona, presented two

concluding that "the geographic clustering of the earliest known cases of Covid-19 and the proximity of positive environmental samples to live animal sellers

."

Chinese researchers have always defended that they have found no trace of the virus in the thousands of animal samples taken from the market, but the WHO insists that these findings prove little: none of the samples included raccoon dogs and red foxes, two species very susceptible to the coronavirus that were in the inventory of the Huanan market.

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