New study reinforces theory Covid emerged at Chinese market - AFP

A study into the origins of COVID-19 on Thursday provided new evidence supporting the theory that humans first contracted the virus from infected animals on the Chinese market in late 2019, UNN reports citing AFP.

Details

The study, published in the journal Cell, is based on more than 800 samples collected from the Huangan seafood market in Wuhan, where wild mammals were also believed to be sold.

The samples were collected in January 2020 after the market closed and were not taken directly from animals or people, but from the surfaces of counters where wild animals were sold, as well as from drains.

From the data shared by the Chinese authorities, "we cannot say with certainty whether the animals (at the market) were infected or not," said Florence Debarre, co-author of the study.

However, "our study confirms that at the end of 2019, there were wild animals in this market, including raccoon dogs and civets," said an evolutionary biologist from the CNRS research agency in France.

"And these animals were in the southwestern corner of the market, which is also the area where a lot of SARS-CoV-2 virus, which causes COVID-19, was found," the scientist said.

These small mammals can contract human-like viruses, which has led to the suspicion that they serve as an intermediate host between humans and bats, from which SARS-CoV-2 is thought to have originated.

The presence of these animals in the Huangan market has previously been denied, despite some photographic evidence and a 2021 study.

Numerous parts of one kiosk tested positive for the COVID virus, including "animal carts, a cage, a garbage cart, and a wool/feather removal machine," the study says.

"These samples contained more DNA from wild mammalian species than human DNA," it adds.

Mammalian DNA was detected in samples that tested positive for COVID from this kiosk, including those from palm civets, bamboo rats, and raccoon dogs.

"These findings indicate either that the animals present in this stall were spreading the SARS-CoV-2 detected on the animal equipment or that people with early unreported cases of COVID-19 were spreading the virus in the same location as the detected animals," the study says.

The study also confirms that the "last common ancestor" of the COVID virus strain found in samples on the market was "genetically identical" to the original pandemic strain.

"This means that an early variety of the virus is showing up in the market - as you would expect if that's where it originated," explained Debarre.

James Wood, an infectious disease epidemiologist at the University of Cambridge who was not involved in the study, said the research "provides very strong evidence that wild animal counters at Wuhan's Huangan seafood market are the origin of the COVID-19 pandemic.

Addendum 

Almost five years after the emergence of COVID, the international community has not been able to determine with certainty where the virus came from.

The first cases were detected in the Chinese city of Wuhan at the end of 2019, but fierce debates arose between the supporters of the two main theories.

One is that the virus leaked out of a laboratory in Wuhan where related viruses were being studied, and the other is that people contracted COVID from an infected wild animal sold on the local market.

The scientific community favored the latter theory, but the debate continues.