A team of international virus investigators from the World Health Organization and experts from China said Monday the deadly pathogen behind the global pandemic began in Wuhan, China but virologists were unable to pinpoint with certainty how the virus may have jumped from bats to animals and then humans.
Reflecting the Chinese government’s claims, the leader of a WHO team told reporters during a lengthy briefing that it was “extremely unlikely” that the virus leaked from a Wuhan lab that had conducted extensive researcher on bat coronaviruses.
The State Department, in a report on U.S. intelligence findings made public in the final days of the Trump administration last month, concluded that the origin of the virus remains unknown but that there was strong case it may have leaked from the Wuhan Institute of Virology, China’s sole high-security lab.
The joint WHO-Chinese mission in Wuhan, which spent four hours interviewing officials at the institute during its stay, said it found nothing to support the lab transmission theory.
“Our initial findings suggest that the introduction through an intermediary host species is the most likely pathway and one that will require more studies and more specific targeted research,” said WHO team leader Peter Ben Embarek, a Danish food safety and animal disease expert, said at a press conference.
The team’s research, he added, “suggest that the laboratory incidents hypothesis is extremely unlikely to explain the introduction of the virus to the human population.”
The investigators determined that while bats remain the likely source for the outbreak, even though no bats were detected in Wuhan at a wild animal market thought to be the origin point.
Mr. Embarek told reporters during a nearly three-hour briefing that independent experts involved in the weeks-long inquiry in Wuhan had uncovered new information but had not drawn concrete conclusions about the virus origin beyond earlier theories.
“The possible path from whatever original animal species all the way through to the Huanan market could have taken a very long and convoluted path involving also movements across borders,” Mr. Embarek said.
He added that no animal species could be identified as the host for the bat virus.
Investigators believe the virus originated naturally in bats but noted that infected bats could not be traced to Wuhan, he said.
The first cases of COVID-19, the disease caused by the virus known as SARS-Cov-2, appeared at a Wuhan hospital on Dec. 1, 2019, and later spread worldwide, killing more than 2 million people in the ongoing pandemic.
“In trying to understand the picture of December 2019 we embarked on a very detailed and profound search for other cases that may have been missed, cases earlier on in 2019,” Mr. Embarek said.
“And the conclusion was that we did not find evidence of large outbreaks that could be related to cases of COVID-19 prior to December 2019 in Wuhan or elsewhere.”
Mr. Embarek said there is evidence of wider circulation of the virus in December. “It was not just only a cluster outbreak in the Huanan Market, but the virus was also circulated outside the market,” he said.
The international team, reflecting Chinese government claims, said the virus may have originated on frozen animal packaging at a wild animal market in Wuhan, an assertion other experts have dismissed as unlikely.
WHO in the hot seat
The conclusions are likely to fuel criticisms of the WHO lodged by the Trump administration that it was heavily under the influence of Beijing. Mr. Trump withdrew from the U.N. agency last year over its China ties and early handling of the pandemic, but President Biden reversed that withdrawal in his first week in office.
Circumstantial evidence made public by the State Department suggests a leak from the Wuhan lab, including cases of several workers at the lab who were sickened with COVID-like symptoms; the documented research at the lab on bat coronaviruses similar to SARS-Cov-2; and covert biowarfare work done by the Chinese military at the Wuhan Institute of Virology.
Mr. Embarek said frozen wild animal products sold at the Huanan Market may have been infected and additional research should be conducted.
China’s government has promoted that idea that the virus was introduced to China on frozen food packaging.
“We know the virus can survive in conditions that are found in these cold, frozen environments, but we don’t really understand if the virus can transmit to humans,” Mr. Embarek said.
Investigators in Wuhan went to both the Huanan Market and the Wuhan Institute of Virology.
The basis for claims that virus did not leak from the virology lab appears to be statements from Chinese lab officials themselves.
China has denied the virus leaked from the WIV but does not appear to have provided full access to records and research conducted by the lab. WHO officials said Tuesday they were given extensive access to Chinese reports and research on the virus and its origins, but in some cases were denied the raw data on which the findings were based.
The U.S. government has called on China to fully explain what it knows about the virus origin that experts said is important for preventing future disease outbreaks.
Mr. Embarek said four hypotheses were developed on the virus origin: a direct jump from an animal to humans; infection of humans through an intermediary host species; infection from frozen food; and “a laboratory-related incident.”
The team concluded the pandemic most likely began from an infection through an intermediary host animal, Mr. Embarek said. Because the lab leak theory is unlikely, Mr. Embarek said he would not recommend that researchers devote further study of that hypothesis.
The WHO international team has been in Wuhan since Jan. 14, after a long, tortuous negotiation with Chinese officials over access to the city.
Asked about the Wuhan findings, State Department spokesman Ned Price said Tuesday the Biden administration was waiting to read the full report before drawing any conclusions, but he pressed the Chinese to be transparent and provide full access about the origins and handling of the pandemic.
“It’s imperative that the world learns as much as possible about the earliest days of the COVID-19 pandemic so that we can understand its origins and so, importantly, we can prevent future biological catastrophes,” he said.
Mr. Price noted several times in a briefing with reporters that the bottom line of Jan. 15 report produced by the previous administration was “not conclusive regarding the origins of the coronavirus” and U.S. officials are awaiting more information.