The debate over the origin of Covid-19 has been going on for three years and is torn between two main ideas: SARS CoV-2 was transmitted to humans directly from an animal or the pathogen managed to escape from a laboratory. Amid a lack of data and cooperation from Chinese authorities and a barrage of accusations from the US, much of the scientific community remains confident in the idea that this initial outbreak, like many others, had a natural origin.
This case needed only one thing: genetic evidence from Hunan Market in Wuhan, China, showing that the coronavirus had infected creatures sold there. This week, an international team of scientists and virologists took a big step toward closing this knowledge “gap.”
According to The Atlantic, the study conducted is one of the strongest pieces of evidence supporting the hypothesis that the pandemic originated in animals. “It strongly strengthens the natural origin hypothesis. It’s really a big indication that the animals in that market were infected. There is no other explanation that makes sense,” says Seema Lakdawala, a virologist at Emory University.
At stake are genetic samples taken from market stalls at the time the pandemic began. It is the first raw data accessed by researchers outside of China, which is published by China’s CDC in an open-access genetic database, GISAID.
The samples in question were already known to be positive for the presence of the coronavirus, but previous Chinese analysis showed that “no animal host could be extracted.”
However, new analysis by researchers suggests that this is not the case. The trio and their team identified several samples collected in the Wuhan market that, in addition to testing positive for Covid-19, revealed large amounts of animal genetic material.
Much of this genetic material was consistent with that of the raccoon dog, a small animal from the fox family that is widely traded in this market and other Chinese regions. Scientists argue that the samples prove that animals of this species, which the samples show were present in this market, could be the real origin of the Covid-19 pandemic.
Evidence does not support the supporting hypothesis because these animals are kept in unsafe conditions and in large numbers, along with other species in Chinese markets. It would be more conclusive if the sample was collected directly from an infected animal, detected in that Wuhan market. “But it’s an important step,” points out one of the scientists responsible for the discovery.
So the missing piece of evidence to complete the puzzle is that raccoon dogs and the coronavirus were at the exact same point in the market. So close that the animals could have been infected or infected themselves.
The discovery does not invalidate the hypothesis that other animals have been infected with Covid-19 in Huanan: raccoon dogs may not have been the creature that passed the virus to humans, so searches for the answer will continue.
The recent study was presented at an emergency meeting of the World Health Organization’s Scientific Advisory Group on the Origin of New Pathogens on Tuesday, and the agency has yet to comment on the developments.