Covid-19 probably comes from the wildlife trade, not from the laboratory leak, the researchers claim

A new genetic study is bolting the theory that Covid-19 comes from wildlife trade and questioned the claims of a laboratory leak. The researchers pursued the origins of the virus to animals that were sold in the Wuhan markets and lend the ongoing debate in the US-China tension.

The results, published in cell On May 7, 2025, a natural spillover pointed out, which emphasizes the persistent risks of zoonotic diseases that result from wildlife trade.

Researchers from the Medical Faculty of the University of California in San Diego and her colleagues came to the conclusion that the ancestor of Sars-Cov-2, the virus that causes Covid-19, was created only years before the start of pandemic. The virus originated in West China or Nordlaos only years before appearing and drove to Central China almost 2,700 kilometers. This time frame is too short for the natural spread by his main host, the horseshoe bat, which indicates that it has “a trip” through the wildlife trade, similar to the Sars outbreak in 2002.

“When two different viruses infect the same bat, what comes out of this bat is an amalgam of different parts of both viruses,” said Joel Wertheim, PhD, Professor of Medicine at UC San Diego School of Medicine, infectious diseases and global health. “The recombination complicated our understanding of the development of these viruses because it leads to different parts of the genome with different evolutionary stories.”

In order to overcome this, the researchers focused on non -recombinating regions of viral genomes and enable them to reconstruct the history of evolution more precisely.

The study shows that Sarbecoviruses have been in circulation in circulation of West China and Southeast Asia for thousands of years in circulation of Sars-Cov-1 and Sars-Cov-2 and are spreading with rates similar to their horseshoe bat.

“Hufeisen bats have an estimated food area of ​​around 2 to 3 km and an expansion capacity of the diffusion speed, which we estimated for the Sarbecoviruses related to SARS-COV-2,” said co-senior author Simon Dellicour.

The analysis also showed that the recent ancestors of Sars-Cov-1 and Sars-Cov-2 left their origin points for less than 10 years before they infected more than a thousand kilometers away.

“We show that the original Sars-Cov-1 was circulating in Western China-Just One To Two Years Before The Emergence of Sars in Guangdong Province, South Central China, and Sars China Or Northern Laos-Just Five to Seven Years Before The Emergence of Covid-19 in Wuhan,” Said Jonathan E. Pekar, PhD, A 2023 Graduate of the Bioinformatics and Systems Biology Programs at UC San Diego School of Medicine, today postdoctoral at the University of Edinburgh.