Where did COVID-19 start? Saskatoon lab helps with genetic analysis targeting animal market

A team of scientists, including one in Saskatoon, say they have strong evidence that the COVID-19 virus jumped from infected animals to humans, rather than from a laboratory leak.

Analysis of hundreds of genetic samples provides weak but strong evidence that the origin of the epidemic is linked to the wild animal trade at the Huanan Seafood Wholesale Market, said Angie Rasmussen, author and epidemiologist at the University of Saskatchewan's Vaccine and Infection Disease Organization. .

The study, published this fall in the journal Cell, shows that the virus emerged from a market in Wuhan, China, around the same time as the outbreak began in humans, suggesting it was a place of origin and connected to live animals. was sold there.

“It's very difficult to explain another way, other than that virus was brought there with those living animals and spilled, actually twice., in the community of people in the market,” he said.

There were two main theories about the origin of the COVID-19 pandemic, which was announced by the World Health Organization in March 2020. One was that the virus jumped from an infected animal to a human, which may have been present in the market; the second was that the virus was leaked from the Wuhan Institute of Virology.

Even as the epidemic raged, finding its source quickly became a priority for the world's leading scientists.

While other studies looked at the presence of the virus in the market, this analysis examined the genetic samples that were present in a shortened period of time. This includes samples from animals known to be hosts and transmitters of the coronavirus such as raccoon dogs, bamboo rats and palm civets.

Powerful possibilities for animal communication, research says

The researchers were able to identify which species are present in the tropical areas where the virus spreads.

Analysis does not prove that animals in those areas are infected. However, the proximity of the COVID-19 samples to where their DNA was present means they may not have been carriers, according to the study.

Dr. Lisa Barrett, an infectious disease expert at Dalhousie University in Halifax, said the study was a good example of “very rigorous and unbiased science” that could help prepare for future pandemic responses. It shows the importance of monitoring animal density in relation to humans and monitoring wildlife trade, he said.

“If we don't understand exactly how viruses spread and under what conditions they spread then we will always underestimate, or underestimate at all, where the next threat is coming from,” he said.

“If you don't know why, history tends to repeat itself in the worst ways.”

Studying genetic markers

Rasmussen has been working with an international research team of top virologists since 2020, examining publicly available evidence to investigate the origins of the epidemic. Another Canadian scientist, evolutionist and University of Arizona professor Michael Worobey, is also on the team.

The team's previous research, as well as other peer-reviewed studies, determined the Huanan Market as the likely place where the epidemic jumped to humans, mainly through the association of live animal trade.

Then in March 2023, a large data set quietly became available online at a site where scientists share genetic sequences for research. The same data was used by Chinese scientists to publish study in the journal Nature in 2023.

The research team immediately began analyzing the genetic markers collected from the swabs from the market.

Scientists say the new evidence makes the laboratory leak hypothesis more difficult to support.

All the data analyzed in the latest research – the first cases and the proximity of the market, the animal area, and the two independent spills in people, which happened in different weeks at the end of 2019 – point to the COVID-19 coming from the market. .

“None of this can be explained by a lab leak,” Rasmussen said.

For that to happen, Rasmussen said it would be necessary for a person to be infected in a lab at the Wuhan Institute of Virology and then go to the market without infecting another person. The same would have to happen with the second generation of the virus.

“If we're talking about preventing future pandemics, we need to focus our resources on the most likely problem, there's a problem with thinking that's not supported at all – and that would be the idea of ​​a lab leak,” Rasmussen said.

Why is the belief in lab leaks spreading?

The idea that the COVID-19 pandemic started after a lab leak began to spread in the early days of the pandemic. As more data slowly become available, top virologists – including Rasmussen's team – argue that the evidence strongly points to the possibility of animal transmission.

Timothy Caulfield, a professor at the University of Alberta and an expert on health and science, said that many people who promote the theory of reward are trying to create a widespread distrust of scientific institutions.

“If you don't believe the lab leak theory, you are the enemy,” he said. “It is considered fact, that it has been confirmed that the lab leak is the source and if you believe otherwise you are simply wrong.”

Rasmussen and his colleagues have been the target of cyber attacks for their work.

“We are accused of conducting a propaganda campaign to cover up the real story of the lab leak. But that is not true,” he said.

Caulfield said the idea of ​​a lab leak continues to spread widely, embraced by politicians in the US and Canada and by people who feel compelled to support the beliefs of their political parties.

“The idea that this was a deliberate act of brute force, that's also I think part of, and very much related to the lab leak theory, and one of the reasons we keep hearing about it today,” he said.