Studies Support Theory That Covid Came From Nature

Studies Support Theory That COVID Came From Nature

Two new studies provide new evidence that the coronavirus pandemic originated in a market in Wuhan, China, where animals were sold, supporting the theory that the virus emerged in the wild and not escaped from a Chinese laboratory.

The research, published online by the journal Science on Tuesday, shows that the Wuhan seafood market was likely the epicenter of the plague that has so far killed around 6.4 million people worldwide. The scientists concluded that the virus that causes COVID-19, SARS-CoV-2, likely passed from animals to humans on two separate occasions.


“All of these tests tell us the same thing: They point directly to this particular market in downtown Wuhan,” said Kristian Andersen, a professor in the Department of Immunology and Microbiology at Scripps Research and a co-author of one of the studies. “I myself was pretty convinced of the lab leak until we dove into this very carefully and looked at it much more closely.”

In one study, which incorporated data collected by Chinese scientists, University of Arizona evolutionary biologist Michael Worobey and colleagues used mapping tools to estimate the location of more than 150 of the first reported COVID-19 cases as of December. 2019. They also mapped cases from January and February 2020 using data from a social media app that had created a channel for people with COVID-19 to get help.

They wondered, “Of all the places the first cases might have lived, where did they live? And it turned out that when we were able to analyze it, there was an extraordinary pattern where the highest density of cases was extremely close to this market and very focused on it, ”Wobey explained at a press conference. “Essentially, this applies to both all cases in December and cases with no known link to the market… And this is an indication that the virus started to spread in people who worked in the market, but then it started to spread in the local community,” he said.

Andersen said they also found clusters of cases within the market, “and that clustering is very, very specific to parts of the market” where wild animals, such as raccoon dogs, are now known to be sold and are susceptible to contracting the coronavirus.

In the other study, scientists analyzed the genomic diversity of the virus inside and outside of China, starting with the first genome samples in December 2019 and extending through mid-February 2020. They found that two lineages – A and B – marked the start of the pandemic in Wuhan. Study co-author Joel Wertheim, an expert in viral evolution at the University of California, San Diego, noted that the A lineage is more genetically similar to bat coronaviruses, but the B lineage appears to have started spreading earlier in humans. especially in the market.

“I realize it sounds like I just said a once-in-a-generation event has happened twice in a row,” Wertheim said. But there were certain conditions, such as the proximity of people and animals and a virus that can spread from animals to people and from people to people. Therefore, “barriers to contagion have been lowered to such an extent that we believe multiple introductions should be expected,” he explained.

Many scientists believe that the virus jumped from bats to humans, either directly or through another animal. But in June, the World Health Organization recommended further investigation into whether a laboratory accident could be to blame. Critics had said the WHO was quick to dismiss the lab leak theory.

”Have we disproved the leak theory in the laboratory? No, we haven’t,” Andersen said. “But I think the really important thing here is that there are possible scenarios and there are plausible scenarios, and it’s really important to understand that possible doesn’t mean equally likely.”

The origin of the pandemic remains controversial. Some scientists believe a lab leak is more likely, and others remain open to both possibilities. But Matthew Aliota, a researcher at the University of Minnesota School of Veterinary Medicine, said that in his opinion, the pair of studies “hopefully puts to rest the lab leak hypothesis.”

“Both of these studies really provide convincing evidence for the natural origin hypothesis,” said Aliota, who was not involved in either study. Since it is impossible to take samples from an animal that was on the market, “this is perhaps as close to irrefutable evidence as you can get.”


The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.