An animal market in the Chinese city of Wuhan It was the epicenter of the covid-19 pandemic, according to two new studies published by the journal Science on Tuesday and which claim to have tipped the balance in the debate regarding the origin of the virus.
Answer the question regarding whether the disease arose naturally from animals to humans, or if it was the result of a laboratory accident, it is considered vital to prevent the next pandemic and save millions of lives.
The first article analyzed the geographical pattern of covid cases in the first month of the outbreak, in December 2019, and showed that the first infections they crowded around the Huanan market.
The second studied the genomic information of the first cases to analyze the early evolution of the virus, concluding that it was unlikely to have circulated widely among humans before November 2019.
Both were previously published as preprints or “preprints”, but have now undergone scientific peer review and appear in a prestigious journal.
Michael Worobey of the University of Arizona and a co-author on both papers previously asked the scientific community in a letter to be more open to the idea that the virus was the result of a laboratory leak.
But the findings took him “to the point where I now also think it’s just not possible that this virus was introduced in any other way than by trading wild animals in the Wuhan market”, he told reporters in a call.
Although previous research had focused on the live animal market, the researchers wanted more evidence to determine what really It was the source of the outbreak, not its amplifier.
This required a neighborhood-scale study within Wuhan to make sure the virus was “zoonotic,” meaning it jumped from animals to people.
The first study team used mapping to determine the location of most of the first 174 cases identified by the World Health Organization, finding that 155 of them were in Wuhan.
These cases were piling up around the market, and some of the first patients with no recent history of visiting the market lived very close by.
Mammals known today to be infectious, among them red foxes, badgers and raccoon dogs, all were sold alive in the marketdepending on the team.
two bloodlines
They also linked positive patient samples from early 2020 to those on the west side of the market, which sold live or freshly butchered animals at the end of 2019.
The first cases contrasted how it spread to the rest of the city between January and February, which the researchers confirmed by drilling into social media log data from the Weibo app.
“This tells us that the virus was not circulating cryptically,” Worobey said in a statement. “Truly it originated in that market and spread from there.”
The second study focused on resolving an apparent discrepancy in the early evolution of the virus. The researchers conclude that Before February 2020, there were two lineages of the virus, A and B, and that both were the result of two separate events of transmission to humans, both in the Wuhan market.
Previous studies had suggested that lineage B had evolved from lineage A.
Under this scenario, there were probably other animal-to-human transmissions on the market that they did not manifest as covid cases.
The study concludes that there was unlikely to be circulation in humans before November 2019. Under this scenario, there probably were other animal-to-human transmission in the market that did not manifest as cases of covid.
“Have we disproved the lab leak theory? No, we haven’t. Will we ever know? No,” said co-author Kristian Anderson of the Scripps Research Institute. “But I think the really important thing here is that there are possible scenarios and there are plausible scenarios, and it’s really important to understand that possible doesn’t mean equally likely,” he added.
