Amid accusations of it being made in a lab or purposefully made more infectious and fracturing faith in science, scientists say they have finally determined the origin of COVID-19.

A team of scientists who have been investigating the virus’ origin have published their findings in two separate articles in Science (available to read here and here) and said they are at the end of their search.

COVID-19 almost-certainly jumped from animals to humans in Wuhan’s Huanan Seafood Wholesale Market, with the researchers even pinpointing the most likely section of the market where it occurred.

“The siren has definitely sounded on the lab leak theory,” Professor Edward Holmes, a world-leading expert on virus evolution and co-author of both papers, told the Sydney Morning Herald.

“In terms of what we can reasonably do, with the available science and the science we’ll get in the foreseeable future, I think we’re at the end of the road frankly. There’s not a lot more to mine.”

Professor Dwyer, the director of public health pathology in NSW and a member of the World Health Organisation (WHO) team who travelled to Wuhan to investigate Covid’s origins, agrees with the findings.

“That’s what we thought originally back when we did the first report,” he said.

“This is yet another brick added to the wall of information around zoonotic infection.”

Using Chinese and WHO data, as well as public online maps, photos, business registries, and official reports, the scientists reconstructed a map of the market, including human cases and Covid-postive environmental samples from late 2019.

The market wildlife section was found to have COVID-19 all over it, with eight of the earliest human cases working nearby.

A stall where COVID-19 was found on a metal cage, a machine used to remove hair and feathers from animals, two carts used for moving animal cages, and a nearby water drain, was also visited by Professor Holmes on a trip to Wuhan in 2014 – where he snapped a photo of caged racoon dogs stacked on top of caged birds.

“We can’t prove it is this exact stall but the data is very suggestive,” he said.

Racoon dogs, along with badgers, hares, rats and foxes are among several species of animals that Covid moves easily among, all of which were being sold in the market in 2019.

The racoon dogs supplied to the market came from farms in western Hubei, the Science papers note, which is an area known for extensive networks of caves filled with Rhinolophus bats that carry coronaviruses similar to the one that causes COVID-19.

Professor Edward Holmes photographed racoon dogs being sold in the Huanan Wildlife Market in 2014. Image: Edward Holmes

“Raccoon dogs are a suspect,” Professor Holmes added.

“I think, strongly, there are a whole bunch of animals out there who have viruses like this that we have not sampled yet.”

In their second paper, the team even determined the two viral lineages that were detected a week apart in December 2019, and which one was the most likely one to have been transmitted from animals to humans.

Using computers to simulate the most likely sequence of events that would produce the two strains, which differ by two small changes in their genetic codes, they found it exceedingly unlikely that the virus would jump into humans and then split into two strains.

Instead, they found that it would be far more likely that multiple strains of Covid had already been circulating in animals, with two strains separately jumping to humans.

As for the theory that Covid originated in a lab, you would expect it to be introduced into humans just once – rather than as two distinct lineages – with samples taken from the Huanan market also containing both strains.

“That, I think, is pretty good evidence,” Professor Dwyer said.

Though supporters of the lab leak theory argue that the market is a perfect super-spreader site, introduced by scientists from the Wuhan Institute of Virology, the scientists found that it isn’t the perfect spreader site that people may think it is.

The scientists found that 155 cases in December 2019 were strongly clustered in the suburbs around the market, but that it is a small and rather obscure shopping spot and was among the least-visited of 430 identified possible super-spreader sites in Wuhan.

“It’s like going to Coles in Bendigo on a wet Wednesday afternoon. It’s not a thriving mass of humanity,” Professor Holmes said.

No-one has proved COVID-19 – or even a twin strain – has been at the Wuhan Institute of Virology either, with no epidemiological evidence showing the virus spreading near the institute.

“There’s no emails. There’s no evidence in any of the science. There’s absolutely nothing,” Professor Holmes said.

On top of that, Covid wasn’t detected in any of the tens of thousands of blood donations in Wuhan between September and December 2019, nor in thousands of samples taken from patients hospitalised with flu-like symptoms between October and December.

“What are the odds that two lineages escape from the lab and both make their way into the market and both cause superspreader events?” Professor Holmes said.

“It’s ridiculous. There is no way that can happen.”

Image: Getty Images

This article first appeared on OverSixty.