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How Dangerous Is COVID-19? We Asked An Epidemiologist.


As of Friday afternoon, there are now 33 confirmed cases of the coronavirus in Louisiana, and officials expect it to continue to spread. There’s been a run on toilet paper and food at grocery stores like Costco and Trader Joe’s as people prepare to quarantine. And it’s good to be prepared. But how dangerous is the virus, really?

New Orleans Public Radio talked with Tulane University epidemiologist Susan Hassig.

Q: How deadly is the virus, really? The estimates range between a 1 and 3 percent fatality rate.

The case fatality rate is very dependent upon who gets sick and who we're counting as infected, because the denominator, that bottom number, who's infected, is the base for that calculation. So if we're testing only people who are seriously ill, the numbers are going to be likely to come up with a higher case fatality than if you're testing very broadly, identifying people who are asymptomatic or very mildly ill, but are positive. They don't die, they don't get severely sick, and so the case fatality in that kind of setting is going to be much, much lower.

Q: Like in South Korea, for example.

Exactly right. South Korea is testing a lot more people with far less presence of clinical symptomology. So I think their experience probably gives us the best estimate for the general future of this outbreak.

Q: Based on all that, what's the consensus?

I don't know that we've gotten to the point where we're comfortable with a consensus yet because we are still gathering information. And as we get more information every day, every week from more and more places around the world, we're going to feel more comfortable understanding what the real clinical impact is going to be of this. I suspect it's going to be less than 1 percent.

Q: So how freaked out should people really be?

Well, there's two things we need to think about when we're talking about risk and just what we should be worried about. First of all, the risk of infection is pretty universal because none of us have prior experience with this organism. It's a brand new virus, so we don't have any protection. So if we encounter it, we're probably going to be infected. But everything we're seeing is that for many, many people who get infected, in fact, some estimates are 80 percent — it has very little clinical impact on them. And so they don't get severely ill. They may be uncomfortable for a few days. But the real concern is people who have preexisting medical conditions in terms of a much more elevated risk of severe outcome. So we want to distinguish risk of infection, which is pretty much universal and risk of negative severe outcome.

Q: So you and I seem to be pretty healthy people. But if we encountered it, we'd be pretty likely to get it. And it might just look like a normal flu for us if we don't have preexisting conditions. If we did have something like lupus where we were immunocompromised, it could be very serious?

That is right. Something like — on steroid therapy, cancer chemotherapy, HIV infection, diabetes, cardiovascular disease, chronic pulmonary disease. All of those things could potentially allow the virus to establish a much more aggressive clinical experience for that person.

Q: It seems like the biggest risk here is just the shutdown of services. But doing so is helpful because it slows the rate of community transmission, which then decreases the risk of human services being totally inundated by a ton of cases at once. So how can we balance those things?

It's a really delicate balance because this is a respiratory infection that is transmitted through close proximity and droplets coming in contact with them. And so the reason for some of the decisions about not having, for example, fans attend sporting events when they're occurring is because those seats are very close together in the stands. We really want to try and slow down the spread of this virus so that we don't get a huge explosion of individuals with highly symptomatic experiences all at once being dropped into the health care system. That would be a really, really difficult situation to handle.

Q: Speaking of that, if you're a health care professional while everyone else is running away from this thing and trying to protect themselves, you're sort of running towards it. So what can you do to protect yourself if you're working in the field?

I have a tremendous amount of respect for the frontline health care personnel, EMS, first responders, the staff at all levels in a health care institution, because they're having to deal with this in very real terms every day. It is possible that the protocols, the guidelines are there to help every level of health professional protect themselves from the person who's preparing the food, to the nurse, to the clinician, to the EMS personnel. The keys for respiratory infection are masks, face shields, gloves — in large part — and basic hand hygiene. Again, even for them, not touching their faces is really, really important. But they're in an environment where it is much higher risk in terms of potential exposure than the rest of us. So I have tremendous respect for them.

Q: Is it true that most of us are just going to get this thing eventually?

You know, we don't know for sure, but I kind of think that that may ultimately be the result. My hope is that it will, in fact, kind of be a low-level spread through the population in that it doesn't generate as many individuals at one single time that need intensive medical intervention. But I suspect we can stop a lot or slow it down tremendously with the social distancing techniques, the avoiding crowds, washing your hands, washing your hands, washing your hands. But the area and the population, I think we need to pay a lot of attention to are individuals who we know are potentially fragile, who we know are possibly going to have a bad experience if they become infected. So if you live in a multi-generational household, for example, you want to be really careful about washing your hands before you go interact with grandma, grandpa.

Q: If I'm having symptoms, how should I decide whether or not to get tested? And how do I get tested?

Well, the testing guidelines are generated by the Centers for Disease Control. And so they set kind of the parameters. It's no longer necessary to have a history of travel to China, for example, to get a test. But it is still largely focused on people with clinical symptoms. And so the most important thing you can do is call a health care provider and say that you're concerned that you might be experiencing coronavirus infections and how can they come in to be evaluated and possibly be tested. They're probably going to test you for flu first, because the symptoms for flu are pretty much the same as they are for coronavirus. And we still are in flu season. And but my understanding now is that we have a good supply of test kits actually physically here in Louisiana to handle both the public testing as well as the commercial testing that is now possible. If a clinician orders it, it can be accomplished.

This is a lot to keep up with.

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Tegan has reported on the coast for WWNO since 2015. In this role she has covered a wide range of issues and subjects related to coastal land loss, coastal restoration, and the culture and economy of Louisiana’s coastal zone, with a focus on solutions and the human dimensions of climate change. Her reporting has been aired nationally on Planet Money, Reveal, All Things Considered, Morning Edition, Marketplace, BBC, CBC and other outlets. She’s a recipient of the Pulitzer Connected Coastlines grant, CUNY Resilience Fellowship, Metcalf Fellowship, and countless national and regional awards.

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