Covid-19 origin search abandons lab leak theory, China’s leader in joint WHO mission says

Zhuang Pinghui
·4-min read

Future work on identifying the origins of the new coronavirus which causes Covid-19 will not focus on the “extremely unlikely” hypothesis that it leaked from a laboratory in Wuhan unless new evidence emerges, according to the Chinese lead of the joint World Health Organization-China investigation.

“The expert team agreed unanimously that it is extremely unlikely the virus leaked from the lab, so future virus origin tracing missions will no longer be focused on this area, unless there is new evidence,” said Liang Wannian, a former senior National Health Commission official, in an interview with Global Times, the nationalist tabloid affiliated to party mouthpiece People’s Daily.

Liang Wannian, team leader of the WHO-China joint mission investigating the origin of Covid-19. Photo: Simon Song
Liang Wannian, team leader of the WHO-China joint mission investigating the origin of Covid-19. Photo: Simon Song

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Liang’s remarks followed Tuesday’s announcement by the WHO that the team’s final report, expected this week, had been postponed because it was “simply not ready”.

“What we hear from the technical experts, from the mission members, is that the report most likely will now come out next week,” WHO spokesman Christian Lindmeier said.

Liang denied the report’s delay was due to any dispute among the mission’s experts, who reported at the end of their investigation last month that the lab hypothesis was unlikely. Initial findings suggested the most likely pathway for the virus had been an intermediary host species, which required further study, they said.

“The report was delayed because it involves a lot of content. As scientists, we must try our best to make the report complete, rigorous and scientific, so this process will take a certain amount of time,” he said.

Liang said the team had “candid, deep communication” during the mission with experts from the Hubei Provincial Centre for Disease Control and Prevention, Wuhan Centre for Disease Control and Prevention, Wuhan Institute of Virology and other institutes.

Peter Ben Embarek, leader of the international researchers, previously told Science magazine the mission was not equipped for a full laboratory audit to further assess the lab leak hypothesis, while WHO chief Tedros Adhanom Ghebreyesus said last month that all hypotheses were still open in the search for the origins of Covid-19.

The WHO coronavirus origin tracing mission, which took months of negotiation before foreign experts were allowed to fly to China for the work, was hailed as transparent and science-based in China, but has been criticised elsewhere for being restrained in its work.

In media interviews, some of the experts described heated exchanges over how widespread the disease was in its early stages in the central city of Wuhan.

China insisted the earliest case was recorded on December 8 and that a retrospective study – of the hospital records of 76,000 patients with either fever, acute respiratory illness, influenza-like illness, or unspecified pneumonia – showed no sign of earlier infection.

But Ben Embarek said the radical elimination of cases to fewer than 100 people with symptoms of Covid-19 was too strict. There was also disagreement on the value of testing these patients for antibodies almost a year into the pandemic, when levels may have faded, according to his interview with Science.

Liang denied there had been any “conflict” – just “normal discussions over scientific issues” – and said requests by the foreign experts for access to raw data and meetings with certain people had been met. He said the mission’s work plan had been jointly finalised, including what kind of data would be valuable at the initial stage of its investigations.

China had hundreds of scientists working on data collection, sorting and initial analysis and the experts had been presented with the raw data “one by one”, he said, without elaborating on what data he was referring to.

“For the original data that required special attention, China showed it to the WHO expert group one by one, such as the early case database and epidemiological investigation reports. Chinese and foreign experts fully discussed the data analysis ideas and phase results, further supplemented and adjusted the data analysis framework and produced new data analysis results.”

Liang added that China’s laws prevented the international experts from taking copies of the data from some cases out of the country, and that they fully understood the restrictions.

Gao Fu, head of the China Centre for Disease Prevention and Control, said earlier this month that various institutions in China were still testing blood samples obtained in Wuhan before December 2019 for earlier traces of Covid-19 infections, but no positive results had so far emerged.

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