World Health Organization report says animals likeliest origin of Covid-19, minimises lab hypothesis

The report following the World Health Organization investigations in China, on the origins of the coronavirus and its transmission to humans, is expected to conclude that the origin and transmission of Coronavirus from bats to humans has been made through another animal.

The report from the global mission to Wuhan has therefore been keenly anticipated ever since the expert team left China more than a month ago.

The team proposed further research in every area except the lab leak hypothesis - a speculative theory that was promoted by former US President Donald Trump among others.

The report's release has been repeatedly delayed, raising questions about whether the Chinese side was trying to skew the conclusions to prevent blame for the pandemic falling on China.

The agency said the report deemed it was "likely to very likely" the virus began infecting humans through an intermediary species and "possible to likely" the virus jumped directly from bats to humans.

"We were surprised to find that the specific interaction between ACE2 glycans and the SARS-CoV-2 spike protein is what makes the separation of the virus from cells so hard", says Im, who is a professor of bioengineering, computer science, chemistry and biological sciences, as well as the Presidential Endowed Chair in Health, Science and Engineering at Lehigh.

For example, the study says highly similar viruses have been found in pangolins, another kind of mammal found in Africa and Asia.

China rejected that criticism on Monday.

"Our goal was to characterize SARS-CoV-2 and study the protein-protein interactions during its invasion of human cells to provide more insights into the mechanisms that make this first step in its successful invasion process possible", says Zhang, an associate professor in Bioengineering and Mechanical Engineering & Mechanics at Lehigh.

White House press secretary Jen Psaki said experts from seven different United States government organisations including the Centers for Disease Control and Prevention, the National Institute of Health and the Department of Homeland Security had the report in hand.

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Among researchers working to develop vaccines, treatments and other weapons against Covid-19, the frustration is evident. It was the first immunization out of the gate in the western world, going into the arms of volunteers on January 4.

The possibility of a lab leak as the source of the pandemic was "extremely unlikely", according to a draft copy of the findings obtained by The Associated Press.

The U.S. government has questioned whether the WHO-convened experts were given enough access to reach a reliable conclusion.

Plus, there is evidence the virus was circulating before the Huanan market outbreak - including at other markets.

The findings align with what researchers said last month at the end of their mission to Wuhan, the central Chinese city where the first COVID-19 cases emerged at the end of 2019, and in their subsequent public comments.

However, the World Health Organization report says "the evolutionary distance between these bat viruses and (the coronavirus) is estimated to be several decades, suggesting a missing link".

A handful of academic papers have been published, and several withdrawn, arguing SARS-CoV-2 appeared instantly adapted to infecting humans and suggested it may have been engineered in a laboratory studying SARS-CoV-1, responsible for the 2002-2003 SARS epidemic, or the HIV virus. The report noted that animal products - including everything from bamboo rats to deer, often frozen - were sold at the market, as were live crocodiles.

It pointed to the fact that there was no record of any virus resembling SARS-CoV-2 in any laboratory before December 2019, and stressed high safety levels at the labs in Wuhan.

As the pandemic spread globally, China found samples of the virus on the packaging of frozen food coming into the country and, in some cases, have tracked localized outbreaks to them. But most health experts have said it is unlikely the new coronavirus came from a lab or was engineered by humans.

The report said that the cold chain, as it is known, can be a driver of long-distance virus spread, though the risk is lower than through human-to-human spread.