A market in Wuhan, China, was the epicenter of the COVID-19 pandemic, and the virus emerged from activities connected with the live animal trade, according to research published in Science on Tuesday.
Why it matters: The case-mapping and genetic studies offer some of the strongest evidence yet that the coronavirus jumped from an animal host to humans — a type of zoonotic spillover seen in other outbreaks like SARS, from 2002 to 2004.
What they found: There were two lineages of the virus introduced in humans as early as November 2019.
- The variants over time spread into the neighborhoods surrounding the market and beyond, challenging the idea the market was the source of a single superspreader event.
- Early cases linked to the part of the market where wildlife sales took place resemble cross-species transmissions later observed on mink farms and from infected hamsters to humans in the pet trade.
What they’re saying: University of Glasgow virologist David Robertson told BBC News he hoped the studies would “correct the false record that the virus came from a lab.”
- “In a city covering more than 3,000 square miles, the area with the highest probability of containing the home of someone who had one of the earliest COVID-19 cases in the world was an area of a few city blocks, with the Huanan market smack dab inside it,” per University of Arizona biologist Michael Worobey.
The intrigue: While early patient data showed few of those hospitalized had a direct link to the market, Robertson said, “it’s exactly what we would expect, because many people only get very mildly ill, so they would be out in the community transmitting the virus to others. and the severe cases would be hard to link to each other.”
- A map of samples collected from market stalls showed most that tested positive for the virus were on the southwestern side, where animals like Raccoon dogs and hedgehogs were sold.
Flash back: An unclassified intelligence report into COVID’s origin released last year was inconclusive, stating the two dominant theories — that it came from a lab leak or was naturally transmitted from an animal — remain plausible.
- A World Health Organization-backed team of scientists said in June that available data suggests SARS-CoV-2 had a zoonotic origin and that the theory that the virus escaped from a laboratory needs “further investigations,” per the Washington Post.
The bottom line: Accurately determining the causes of COVID-19 will go a long way toward informing what can and should be done to prevent the next pandemic.