ARI SHAPIRO, HOST:
Several studies released over the past few days offer the most convincing evidence yet that the COVID pandemic started in a seafood market in Wuhan, China. A separate competing theory holds that the pandemic came from a laboratory leak, but the new studies present physical evidence that the virus emerged in the market. NPR's Michaeleen Doucleff is here to tell us about this research. Hi there.
MICHAELEEN DOUCLEFF, BYLINE: Hi, Ari.
SHAPIRO: This is the seafood market we've been talking about from the very beginning of this pandemic, right?
DOUCLEFF: Yes.
SHAPIRO: All the way back in September 2019.
DOUCLEFF: Yes, the Huanan seafood market. This was the site of the first large COVID outbreak. That part is not controversial. Perhaps thousands of people were infected there, and that market has hundreds and hundreds of stalls packed close together. And people there sold all kinds of meat - frozen, fresh and live wild animals.
SHAPIRO: So what's new here? These studies have physical evidence. What is it?
DOUCLEFF: Yeah. So these studies are preliminary. They haven't been peer-reviewed. But one thing they show is photographic evidence that at least two types of wild animals were sold there that could easily catch SARS-CoV-2 and shed it into the air. These are raccoon dogs and red foxes. And until this study, there had been doubts about whether animals like this - you know, that could be actual sources of the virus - were in the market.
SHAPIRO: So photographs of animals that can easily spread the virus - anything else?
DOUCLEFF: Yeah. So these animals - also there's proof that they were held in cages in or near one stall in particular at the market, a stall where scientists actually found a lot of SARS-CoV-2 on surfaces. Michael Worobey led two of these studies. He's an evolutionary biologist at the University of Arizona. He says inside this stall, the virus was found on very specific surfaces, including machines where animals were butchered.
MICHAEL WOROBEY: The samples were very animal-y (ph) - for example, a feather remover, a cart of the sort that we see in photographs that are used for transporting cages but, best of all, a metal cage in a back room.
SHAPIRO: Best of all is a choice of words there. So we're talking about very early in the outbreak, animals in the market, genetic samples from where they were held showing the virus was there. Like, how are they connecting these dots?
DOUCLEFF: Yeah. And he also - they also show that these conditions existed for years. Worobey says about five years before the pandemic, one of his colleagues was actually taken to this exact stall because people were concerned about what could potentially be growing or created there.
WOROBEY: Very much told this is the kind of place that has the ingredients for cross-species transmission of dangerous pathogens.
SHAPIRO: But just to rule out any other possibilities, is it possible that a person could have brought it into the market and spread it to those animals and to other people there?
DOUCLEFF: Yeah. So these papers addressed that one, too. One of them looks at the genetics of the virus found in the market, and it shows that two different variants jumped into people at almost the exact same time. And it shows that these variants, one of which went on to spread all around the world, couldn't have actually evolved in people.
SHAPIRO: So does this end the lab leak theory? Does this rule it out?
DOUCLEFF: You know, I was talking to Jeremy Kamil about this question. He's a virologist at Louisiana State University Health Shreveport and not involved in this research. He says these studies, along with several others published recently, are really tipping the scales toward an animal origin.
JEREMY KAMIL: Absolutely pushing it that way. It doesn't exclude other hypotheses entirely, but a number of the things that it doesn't exclude are other related - like, to the wildlife trade. Like, could people who were trafficking in these animals and bringing them to Wuhan have been infected and brought it to the market?
DOUCLEFF: He says, you know, the picture is really becoming clearer and clearer that the pandemic most likely started in the market and came from an animal.
SHAPIRO: NPR's Michaeleen Doucleff, thanks for walking through this investigation with us.
DOUCLEFF: Thank you, Ari.
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