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Did COVID-19 start in bats? How did it transfer to humans? Answering your coronavirus questions

KGW's Brenda Braxton spoke with PSU biology professor Ken Stedman, an expert on viruses and the spread of viruses.

PORTLAND, Ore. — With so much new information coming out every day about the novel coronavirus, also known as COVID-19, we wanted to get your questions answered by an expert.

KGW anchor Brenda Braxton had a 25-minute interview with Ken Stedman, a biology professor at Portland State University, an expert on viruses and the spread of viruses. He spent the time talking about the origins of COVID-19 and answering questions you sent us via text.

You can still text your questions to 503-226-5111 and those questions may get answered on TV or online. If you text “facts” to that number, you’ll be sent a link to KGW’s coronavirus coverage.


QUESTION: I’ve heard a lot of doctors and lot of people talk about how coronavirus started in China, in Wuhan, in a wet market with lots of different animals. But can you walk me back maybe even further than that and tell me how the heck we got here. How did COVID-19 end up causing such a problem for us stateside. What do we know about its origins?

STEDMAN: That’s a great question. The answer is we don’t completely know. But what we’ve been able to do is a molecular process, kind of a detective search to try and figure out where this particular virus is causing the COVID-19 disease. We actually call it now SARS-CoV2. This SARS-CoV2 pretty clearly originated in bats. The reason we know that is if you look at bats, bats have a massive amount of diversity of coronaviruses in bats, way more coronaviruses in bats than in any other animal anybody’s ever seen. We’ve got four or five different coronaviruses that infect us, but bats have probably hundreds of different coronaviruses. That’s the first indication that it probably came from bats, because there are way more coronaviruses in bats. But then, if you also look specifically at the genes that are present in these particular viruses that are causing COVID-19 right now in us, those are extremely similar to a bat virus that was found by the Chinese in some caves in China, that is not identical to the one which is infecting humans now, but it’s so similar that it’s highly likely that this virus, which is infecting us and the one that’s infecting bats, came from a common ancestor probably not that long ago. So probably there was a bat virus and that bat virus somehow got into humans. That’s where the big question is right now. We don’t completely understand what that is.

WATCH: Live chat | How we got here with the coronavirus

QUESTION: What might have been one of the chain of events that went from bat to human? What happened in between?

STEDMAN: Great question. We don’t know. But again, if you look at these sequences and you think about these wet markets in China, where you have a lot of live animals that are for sale, some of them legally, some of them less legally, that appears to be at least where this particular coronavirus, which is infecting us now and is causing these epidemics, that’s where there’s a big focus of this particular virus. So, probably what happened, is there were some wild animals in that market that were infected by a bat virus originally. How, you may ask, how does a bat virus end up in some of these animals in a wet market? What we think happened, again this is projection, but given the molecular detective work that a lot of people have been doing, not me, but lots of other people have been doing, it looks as if this particular virus probably came out of a bat, and the way things come out of bats is usually in their guano [excrement of seabirds and bats], so, and coronaviruses in bats are mostly intestinal viruses, they’re not respiratory viruses, quite why that is is not entirely clear, but it probably came out in the bat guano, and then some other animal either ate that guano, was exposed to it somehow, that then ended up in the wet market. It might have been pangolins, and you might have heard of the pangolins before.

QUESTION: I think not many people are familiar. Can you explain what a pangolin is?

STEDMAN: A pangolin is kind of a cross between an ant-eater and an armadillo. They’re actually really cute, go look them up online. They’re these really fascinating mammals which have scales, they’re the only mammals which have scales. Those scales are really prized in traditional Chinese medicine, even though they’re illegal to be traded in, there ends up being a lot of trade of them. Apparently, the meat is also something a lot of people are interested in. Why pangolins, you may ask? It turns out as I mentioned that the virus infecting us is very similar to bat viruses in almost all of its genes, but there’s a small part in the virus genes that’s infecting us that looks more like a pangolin virus than it does like a bat virus.

QUESTION: Oh, interesting. So then they’ve intermingled perhaps. So we’ve got the bat and the pangolin and this new virus that has morphed and is passed to humans if they, what, eat the pangolin? How does that happen?

STEDMAN: Presumably. Again, great point. Probably there was this interaction that took place, we call it recombination in the virus world. That probably would have happened in the pangolin or some other animal. In the case of SARS, back in 2003, it was probably pretty clearly a civet cat, where this happened. And again, this is recombination that happened between the different viruses. But then, after that, it’s in this particular animal, then it has to transfer somehow to humans. How did that happen? Probably not by being eaten. That’s kind of unlikely. Somehow it’s ended up in our lungs. Clearly now, this particular coronavirus, and all coronaviruses in humans, are really mostly spread through respiratory tract, sneezing, coughing, etc. So, maybe the pangolin sneezed or there’s just lot of aerosol. All of these markets in China are incredibly packed, everything’s very, very close together, all the animals are packed, cages stacked on top of each other. So it could be some kind of fecal matter or aerosol droplets from the animals then spread to people in the market and then from there, spread then to other people.

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QUESTION: Wow. That’s an amazing progression of what could be. Like you said, we don’t know 100%. Now that it’s here, what are some of the things we can do to stop the spread, or at least slow the spread?

STEDMAN: What we can do. Basic hygiene is one of the major things we should do. Hand washing. That’s probably one of the very few things I’ve changed in my normal routine. Wash my hands a lot more. Wash them for a long time, lots of soap, back and front. That’s one thing, seems to be the best way to slow down the spread, is literally this hand washing. Second thing to do, is if you are sick, stay home. Don’t go and spread whatever you have to everyone else who is out there. One of the hardest things to do is don’t touch your face unless you’ve washed your hands right beforehand. All of us are really bad at touching our face. The other thing to do, not so much in terms of stopping the spread of the disease, but just being prepared, as you say, facts not fear. What I like to say is to be prepared, don’t be scared. Think through that process what you would do if you had to stay home for two weeks and were quarantined. If your kids weren’t in school. … Also, just be a little bit flexible about things. It may not be the student who is sick, maybe their kids are sick, maybe their parents are sick. And that’s actually much more likely, particularly with this coronavirus, it’s the old people who are getting sick. It’s not the kids. Another huge, open question now is what is the role of kids in the disease?

QUESTION: What do you mean by that?

STEDMAN: Are [kids] getting sick but we’re not seeing it but they’re still transmitting. Are they not getting sick at all? These are questions we really don’t have a good answer to right now. That’s one of the things a lot of researchers are trying to understand now, what is the role of children? What is the role of schools? This is important. Should we be closing schools? Should we be leaving them open? What’s the appropriate thing to do? There are definitely arguments one way and the other. The more we can find out about it the better. A lot of that gets to one of the things I’m really adamant about, and you can ask any of the people I work with: data, data, data. I’m a complete data junky. We need more data about the coronavirus, particularly what’s happening with the kids, to figure out what’s the appropriate response to have. Is closing schools the right thing to do? It’s incredibly disruptive. So what do you do about that?

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QUESTION: And we’re getting more data every day. We’re learning more. I’m going to get a couple questions from viewers. Do things spread faster in the warmth or cold, and are you worried about the spread?

STEDMAN: That’s a great question and the answer is we don’t have data on this. We don’t know, at least not for the coronavirus. For flu, influenza, definitely there is more spread during the colder parts of the year. It’s still not entirely clear why that is, which is another reason to get your flu shot.

QUESTION: So, influenza and coronavirus are two different things. How does the flu shot morph into protection for anything else?

STEDMAN: That’s a great question. Just to be very clear, you’re exactly right, flu and the coronavirus are very different viruses. But we have a vaccine for flu, we don’t have a vaccine for the coronaviruses. So, if you’re vaccinated for flu, even if you do get the disease, really good data show that the symptoms that you get are a lot lower if you have been vaccinated. That means you don’t have to go to the ER. You don’t have to see your doctor. If you don’t go to the ER, you’re not going to be using the resources that other people will be using for coronaviruses, and you’re less likely to be exposed to someone who might have a coronavirus and might be in the ER.

QUESTION: Someone is asking can you get the coronavirus more than one time?

STEDMAN: Can you be infected by the coronavirus more than once? Again, open question, we don’t have great data on this. It’s probable that at least once you’re originally infected, then you will get an immune response and that will protect you over some period of time from getting re-infected. The big question is, how long is that period of time. Is it a year? Is it two years? The data that people have looked at from SARS looks as if probably on the order of a couple of years. So you might need, considering we’ve developed a vaccine, and we’re trying really hard to develop vaccines, that once you have a vaccine, you might need to get a booster, actually not unlike what we have now with the seasonal influenza, after a couple of years. But these are all things that are way down the road right now.

QUESTION: I know it’s a complicated process, but why does it take so darn long to get a vaccine? You’ve got all these people around the world working on it, but they’re still saying it’s maybe a year out.

STEDMAN: The main thing as far as vaccines concerned is safety. You don’t want to take someone who is not sick and by giving them a vaccine make them sick. The safety processes you have to go through for drugs, but particularly for vaccines, because you’re not giving to somebody who’s sick, you’re giving them to someone who’s not sick, you want to make sure there’s complete safety. So the first thing that happens is you do testing in animals, just to make sure that’s something doesn’t make the animal sick, but mice aren’t humans, so you have to then check. Once you’ve gone through a bunch of animal studies, then you do safety studies in humans, what they call a Phase 1 trial. Then, you do some safety and efficacy trials, which then takes another multiple months. And then finally you do a Phase 3 trial, which takes another probably six months or so. Literally the safety and efficacy takes about a year. And that’s partly why we don’t have a SARS vaccine, because it was all done by the time the vaccine was developed. And for the Ebola vaccines, which are great vaccines, by the way, those were just being developed while the big Ebola outbreak was happening, and it was right at the end when they were able to be tested. Now, in the DRC, the Democratic Republic of Congo, they’re actually able to use these vaccines because they’d been tested in the last outbreak. And because people had been developing them, it turns out the Ebola vaccine was developed decades ago and fortunately, people had done enough work that they were able to start with that clinical testing when they had the West Africa outbreak.

QUESTION: Can someone who has been around the virus but not tested positive be a carrier?

STEDMAN: The answer is, again, we don’t really know. We suspect that when someone is around someone who has the virus, who has been diagnosed, that they could potentially be a carrier. And that’s one of the reasons we’ve been testing people who are really close contact, particularly family members of people who have been diagnosed. These are people who the public health groups – Oregon.gov, Oregon Health Authority, are great places to go and get more information.

Visit Ken Stedman's website at extremeviruses.org and follow him on Twitter @XtremeVirusProf.

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