No joy on source of Covid-19 for WHO team
A World Health Organisation delegation that travelled to China to investigate the origins of COVID-19 has failed to identify the source of the pandemic.
A World Health Organisation delegation that travelled to China to investigate the origins of COVID-19 has failed to identify the original source of the pandemic, but has left open the possibility that the disease originated in a region other than Wuhan.
The WHO-convened Global Study of the Origins of SARS-CoV-2 reported its findings in a press conference in China at the end of the investigators’ two-week scientific visit to Wuhan.
They said the search for the origin of SARS-CoV-2 was still a “work in progress”.
The delegation said its investigations had followed four main hypotheses: the introduction of the virus through “direct spillover” from infected animals, the introduction to humans through an intermediary host, transmission via cold chain products, and the theory that the virus may have escaped from a laboratory.
Scientist Peter Ben Embarek, who was part of the delegation, said the laboratory theory was “extremely unlikely” and had been ruled out.
He said the introduction of SARS-CoV-2 through an intermediary animal host was the “most likely” theory that would be the focus of further studies.
It was also possible there was direct transmission from an animal to a human, or that animal products were the source of the virus.
The investigators were not able to identify the animal that could have acted as an intermediary host but it was unlikely the disease had come directly from bats into humans.
Liang Wannian, the team leader representing China in the global study, said there was no evidence SARS-CoV-2 was circulating in Wuhan before December 2019.
However, unpublished studies in various countries indicated the virus may have been present elsewhere before Wuhan.
“These studies from different countries suggests that SARS-CoV-2 (was) circulating preceding the initial detection of cases by several weeks,” Mr Liang said.
“This indicates the possibility of the misreported circulation in other regions.”
The delegation has ruled out the Hunan seafood market as the source of the virus, but there was “no obvious cluster of exposure” beyond the market.
The global team has vowed to continue its scientific efforts to track down the original source of the virus.