The virus that caused the COVID-19 pandemic is "extremely unlikely" to have originated in a lab, but most likely jumped from an animal to humans, according to a World Health Organization report released on Tuesday by a joint international and Chinese team probing the virus' origins.
The 120-page report said the virus most probably jumped from an animal, potentially a bat or pangolin, to an unknown intermediate animal host and then to humans. However, the path of transmission is still not known.
"There is no record of viruses closely related to SARS-CoV-2 in any laboratory before December 2019, or genomes that in combination could provide a SARS-CoV-2 genome," the report said.
"In view of the above, a laboratory origin of the pandemic was considered to be extremely unlikely."
The report said that the two most likely scenarios to explain the emergence of COVID-19 both involve the transmission of the virus from animals to humans.
"So far, we have not been able to document any substantial transmission of SARS coronavirus in the months preceding the outbreak in December," Thea Fisher, a member of the international team, said at a news conference on the report on Tuesday.
Peter Ben Embarek, a Danish food safety and animal disease scientist who heads the international team, said the joint team looked into all scenarios.
"We try to stay with the arguments we have, the hard facts we have," he said.
He called it "a huge report" with a lot of new knowledge, data and information, and added that information will continue to come out after the initial studies.
He also praised the good collaboration between the Chinese and international experts.
"I think the size of the report, and the amount of material and results and analysis and data in the report, speaks for itself in terms of how the collaboration went," he said.
"There would never be anything like that if we did not have a very strong, good collaboration with our colleagues in China," Embarek added.
The report was written by a joint international team made up of 17 international experts and 17 Chinese experts under a mandate from the World Health Assembly, the decision-making body of the WHO. The United Nations Food and Agriculture Organization participated as an observer.
The team conducted a joint study from Jan 14 to Feb 10 in Wuhan, Hubei province, following initial online meetings, according to the report.
Peter Daszak, a member of the international team, tweeted, "I do hope people actually read the huge amount of new data in the report!"
Q: The World Health Organization has released the report of the joint WHO-China study of origins of SARS-CoV-2. What's China's comment?
A: China has taken note of the report released by WHO. We commend the Chinese and international experts who have taken part in this joint study for their commitment to science, tireless industry and professionalism.
China has always been a supporter for global scientific research on the source of the virus and its transmission routes. We co-sponsored the WHA resolution on COVID-19 and support WHO-led cooperation on zoonotic source research among member states. Despite the daunting task of domestic prevention and control, China twice invited WHO experts in for study of origins. From January 14 to February 10 this year, Chinese experts and international experts from WHO and ten countries formed a joint team and conducted joint research for 28 days in Wuhan. The Chinese side offered necessary facilitation for the team's work, fully demonstrating its openness, transparency and responsible attitude.
Study of origins is a matter of science, which should be jointly conducted by scientists all over the world. To politicize this issue will only severely hinder global cooperation in study of origins, jeopardize anti-pandemic cooperation, and cost more lives. It would run counter to the international community's aspiration for solidarity against the virus.
Study of origins is also a global mission that should be conducted in multiple countries and localities. We believe the joint WHO-China study will effectively stimulate global cooperation in origin-tracing.