According to the study, which was published online Tuesday by the journal Science, the Huanan Seafood Wholesale Market in China was the epicentre of the pandemic that has now killed nearly 6.4 million people worldwide.
Multiple new studies add to the evidence that the coronavirus pandemic began in a Wuhan, China market where live animals were sold, supporting the theory that the virus indeed emerged in the China.
Scientists believe that the virus that causes Covid-19, SARS-CoV-2, spread from animals to humans twice.
The World Health Organization was criticised globally for dismissing the Wuhan lab leak theory too quickly as well as for not holding China resposonsible for hiding the pandemic.
“All this evidence tells us the same thing. It points right to this particular market in the middle of Wuhan,” said Kristian Andersen, a professor in the Department of Immunology and Microbiology at Scripps Research and coauthor of one of the studies. “I was quite convinced of the lab leak myself until we dove into this very carefully and looked at it much closer.”
Have we proven the lab leak theory wrong? No, we haven’t, said Andersen. But I think what’s really important here is that there are plausible scenarios and possible scenarios, and it’s critical to understand that possible does not equal equally likely.
Andersen added that they discovered case clusters within the market as well, “and that clustering is very, very specifically in the parts of the market” where they still know people were selling wildlife susceptible to coronavirus infestation, such as raccoon dogs.
In another study, University of Arizona evolutionary biologist Michael Worobey and his coworkers used mapping technology to evaluate the areas of more than 150 of the earliest reported Covid-19 cases from December 2019. They also used information from a social media app which had formed a channel for individuals with Covid-19 to get help to map cases from January and February 2020. They wanted to know where the early cases lived out of all the possible places. And it turned out that when Worobey and his team looked at it, there was this incredible trend in which the largest percentage of cases was also extremely close to and very centred upon the Wuhan market.
Scientists in another study examined the virus’s genomic diversity both within and outside of China, beginning with the first sample genomes in December 2019 and continuing through mid-February 2020. They discovered that the pandemic began in Wuhan with two lineages, A and B. Lineage A is more genetically similar to bat coronaviruses, according to study coauthor Joel Wertheim of the University of California, San Diego, but lineage B appears to have spread earlier in humans, at the market.
“Now I realize it sounds like I just said that a once-in-a-generation event happened twice in short succession,” Wertheim said. But certain conditions were in place — such as people and animals in close proximity and a virus that can spread from animals to people and from person to person. So “barriers to spillover have been lowered such that multiple introductions, we believe, should actually be expected,” he said.
Many scientists believe the virus spread from bats to humans, either directly or indirectly. However, in June, the World Health Organization recommended a more thorough investigation into whether a lab accident or if China was to be blamed for the outbreaks.
The cause of the pandemic is still unknown. Some scientists believe a lab leak is more likely, while others are open to both scenarios.