Compelling new evidence tracks COVID’s origin to Wuhan market

From the start of the pandemic, scientists have tried to determine exactly where and how the novel coronavirus spread to humans. New studies conclude the virus first emerged from a live-animal market in Wuhan, China. One of the authors of a study, Angela Rasmussen, a virologist at University of Saskatchewan's Vaccine and Infectious Disease Organization, joins William Brangham to discuss.

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  • Judy Woodruff:

    From the start of the pandemic, scientists have tried to determine exactly where and how this novel coronavirus spread to humans. Did it emerge naturally from the animal world and get transmitted to people in Wuhan, China, or from a security breach at a research lab, also in Wuhan?

    That has been the subject of an ongoing debate.

    William Brangham is back with details about new studies published yesterday in the journal "Science" that point to the live animal market.

  • William Brangham:

    Judy, trying to understand COVID's origins has been a complicated and politically fraught undertaking for almost three years now.

    The Chinese government has been accused of impeding a full investigation. But this new research attempts to get the clearest picture to date.

    And I'm joined by one of its authors. Angela Rasmussen is a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan.

    Dr. Rasmussen, great to have you back on the "NewsHour."

    So, the — at the beginning of the pandemic, a lot of attention was focused on this live animal market. And you and several of your colleagues, including Michael Worobey, have got some pretty strong evidence in your paper that indicates this was the epicenter of the outbreak.

    What is that evidence?

    Angela Rasmussen, University of Saskatchewan: We plotted all of the early cases from December of 2019 on a map of Wuhan, whether they were associated with the Huanan market or not, and many of them were.

    This was identified as a place that was important early on in the outbreak investigation. We found that, whether those cases were associated with the market or not, whether they had been to the market or not, they really clustered around the market and formed almost a circle around the market, where the market was in the dead center.

    Another piece of evidence is that we know that live animals, including some that were susceptible to SARS-Coronavirus-2 to infection, were being sold at the Huanan market, including in November and December of 2019. And, furthermore, there were environmental samples collected from the site of the market where these animals were sold that were positive for SARS-Coronavirus-2.

    That really strongly indicates that those samples, those environmental samples, may have come from the animals. And on top of that, those samples were often collected from things associated with animals, such as cages, hair and feather removal devices, and carts.

    And then, finally, there were actually two different genetic varieties, or variants, of SARS-Coronavirus-2 that were at the market, lineage A and lineage B. Initially, we thought that lineage B was spreading at the market, but we didn't understand that lineage A was also there, until it was found in an environmental sample.

    This suggests that really there had to be two separate introductions into the market. And the only thing that explains this is two people independently coming into the market and being infected with lineage B and lineage A about a week apart.

  • William Brangham:

    The other may major theory that has been bandied about over the last few years is about the Wuhan Institute of Virology, which is a Chinese lab, where Chinese researchers and some American-funded researchers were studying coronaviruses.

    And the theory was that the virus somehow got out of that laboratory and then spread amongst people. What does your research indicate about that theory?

  • Angela Rasmussen:

    So, our research actually indicates nothing about that theory, other than the early cases were not clustered anywhere near that Wuhan Institute of Virology, which strongly suggests that nobody actually in the lab was infected.

    On top of that, no evidence whatsoever has emerged since the very beginning of the pandemic that suggests that the Wuhan Institute of Virology was involved in the outbreak in any way.

  • William Brangham:

    Some of your fellow virologists have said that, given that some of this research relies on Chinese data, that we have to take this with a grain of salt, because the Chinese have a great deal of interest in pointing a finger at a more natural — quote, unquote — "natural" emergence of this virus at the market.

    Do you share that concern?

  • Angela Rasmussen:

    I disagree with that for two reasons.

    And, first, origins investigations are usually very light on evidence. And the evidence bases are never complete. We found that we certainly had enough evidence to come to the conclusions that we came to with a high level of certainty.

    But the second objection I have to that is the fact that, actually, a market outbreak looks really worse for the Chinese government than a lab accident. And the reason for that is that the live animal trade was integrally involved in the outbreak of SARS-Coronavirus-1 in the early 2000s.

    And, at that time, the Chinese government said that they were going to crack down on the live animal trade and regulate it to be more safe. And, ultimately, it became illegal. That means that, essentially, all of this live animal sales and trading was occurring outside of the law.

    And so it was completely unregulated. And it is, I think, very embarrassing, given that that is exactly the same circumstances under which SARS-Coronavirus-1 emerged.

  • William Brangham:

    So, is it your sense from all of your investigations into this that, are you — do you feel — I know this is not the scientific term — but 100 percent sure that this market was the — was the epicenter, or is this just the best science we have today, indicating that's the most likely case?

  • Angela Rasmussen:

    Well, so I personally do feel 100 percent sure.

    But, of course, as I mentioned, there are other possibilities that could explain it. However, those possibilities are vanishingly unlikely. So I personally am very certain that this does explain where the virus came from.

    Now, that said, there are still many open questions. How did those animals get infected? Which animals were infected? Where did they come from? Who was exposed to them prior to coming into the market? There are many open questions that still need to be answered.

    But I feel that we really have closed the book on where the outbreak began. And that was at the Huanan wholesale seafood market.

  • William Brangham:

    All right, Dr. Angela Rasmussen at the University of Saskatchewan, great to see you. Thank you so much for being here.

  • Angela Rasmussen:

    Thank you so much, William.

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