The head of the WHO delegation who recently visited China to investigate the origins of the pandemic expressed frustration on Saturday over the lack of access to raw data during this mission, saying more was needed to detect possible early cases of Covid-19.

"We want more data. We have asked for more data," said in an interview with AFP Peter Ben Embarek, who went with his team for a month to Wuhan, where the coronavirus responsible for the epidemic was discovered in December 2019. "There is a set of frustrations but also realistic expectations as to what is doable within a given time frame", he added, before hoping that the requested data would be provided, allowing go further.

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These experts from the World Health Organization completed their mission earlier this week without reaching any definitive conclusions.

They believe that Covid-19, which has already claimed an estimated 2.4 million lives worldwide, has its origin in bats and may have been transmitted to humans via another mammal.

However, these experts do not know where and when the pandemic really started, even if no major outbreak was reported in Wuhan or elsewhere before December 2019.

The doubts of the United States

Peter Ben Embarek pointed out that his team would have liked to have access to raw data on previous cases of illnesses like pneumonia and influenza.

Before the WHO mission began, Chinese scientists had identified 72,000 of these cases between October and December, of which it was not impossible that they were in fact cases of Covid-19.

After applying a series of criteria, they ended up establishing a list of only 92 cases, according to them, deserving of being examined to find out whether they could have been cases of contamination by the coronavirus.

67 of them gave rise to serological tests which were all negative for Covid.

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"We are trying to understand the process which led to go down from 72,000 to 92", said Peter Ben Embarek in this regard, who lamented not having received a response concerning the nature of the criteria used to do so.

John Watson, a British epidemiologist on the WHO team, however, stressed that while his Chinese colleagues had not transmitted all the raw data in their possession, they had shared "a great deal of detail" about their work.

The United States for its part announced Saturday to have "strong concerns" about the first results of the WHO investigation, asking Beijing to provide more information.

"To better understand this pandemic and prepare for the next one, China must make its data on the first days of the epidemic accessible," Washington insisted.

Peter Ben Embarek for his part acknowledged that if it would have been of course "fantastic" to have been able to go to Wuhan earlier, "it is certainly not too late" to know more about the origin of the pandemic .