Why does COVID-19 make some people sicker than others? l FiveThirtyEight

FiveThirtyEight reporter Kaleigh Rogers explores why some young COVID-19 patients get so much sicker than others.
3:00 | 05/01/20

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Transcript for Why does COVID-19 make some people sicker than others? l FiveThirtyEight
Kelly we've heard a lot about the risks and have been nineteen on older people they know you've been looking into you whites and younger people are getting really sick as well. So to start off let's just talk about numbers at just how many young people who. Otherwise are healthy are getting me. Okay. If you look at the United States. I've got some numbers here from the CDC. And they found that 34% of the confirmed cases were in patients under the age of forty so then. Of the patients that we know are hospitalized about 20% of those were Anita 45. And those that we know where it needs to ICU 12% were under 45. So obviously the more severe gets the less likely that you have younger people in those groups. And SEC also reports that the case fatality rate. Is less than 1% for people between the ages of twenty and 54 excellent bat against severity tends to get worse the holding each repeated into. What I was trying to do take a look at was those that are out liars and young healthy group who are gaining a severe illness who are going icu or dying because that's unusual. And we'll see this that basically any kind of infection is always going to be a handful of people who seem healthier otherwise knotted at great risk but somehow stolen getting a severe infection. That's true basically any kind elements that we see and it's true coded. And such as trying to pick a look at what might be causing that in this particular disease. So what are some of the hypotheses about why certain. Young people are getting so severely. Rates of this thing is that scientists are hypothesized thing you know we don't know for sure yet because we still just beginning to sort this research. But one of the things is genetic so we do know that your genetics can determine how your body reacts to different infections are rare immune system is built and functioning. And so they want to take a look and see if there's any kind of genetic. Mutation that might predispose somebody to being at risk for or worse infection that other people in that otherwise young healthy group. Of their peers. This is something that we we have seen with other diseases you can have different genetic mutations that can make you more likely to get an infection or actually. Be protected and make you less likely to get certain infections. Like HIV it's a genetic mutations that can make you less likely to get out of action. So we know there's. President there for genetic having a role in this from the religious right to investigate and see what could be playing a role here. So just be clearly this is it genetic mutation that. May be no one would have ever known had covic nineteen not emerged in the population like it's not something that necessarily. Would have affected people's immune systems generally this is at mutation that might be very specific Q how. This corona virus. You don't makes you sick. Definitely so for example one of the lines that researchers are really curious about it and looking at is called ace to. Proteins this is like a pro team that lives on the surface of some yourself including yourself in your respiratory system. And this particular virus the corona virus uses in spite pro team she news. Go into this eighths to accept her and that sort of like locking key scenario where that ace to his moloch and that's by protein is the key. And just as there that spike routine is that. Basically those little things sticking off of the illustrations of the virus that you might have seen that kind of give it that crown in fact. Yet yes that's the spikes of the crowd and that's in the works with what the key the lock which is happy engaged as well. Which is what the virus is trying to do what's in danger salsa that it can reproduce and then. But and the more cells. And so. There's a chance that there could be a genetic mutation where some people money for example produce a lot more of this ace two were sector arm yourself. And you can imagine there's a bunch more of these sort of poorly into the cell and activists the virus. Even more opportunities to invade and that could mean because a more severe infection. This is all this had. He says at this point but it's one area that could have a particular very specific. Wayne that the virus is taking advantage of the genetic mutation that might occur in some people what are some other hypotheses that scientists have. Britain and Ireland. That they're considering taking a look at his club infectious doses that's like the amount of virus your first exposed to advocate she's sick. And you can again imagine if you are. Working in a healthcare setting in the icu in your. Around infected patients all day long you're gonna have exposure to a higher amounts of the virus than someone who may be. Just went to the grocery store once and you know touched the surface on its knees that's 28 different amount of virus that your first exposed to. And might have a difference in how severe infection is not something they're investigating. It that's a chant that it could have nothing to do it and it does sometimes a micro you know it only needs one. And then it just multiply quickly after the Connecticut won her hundred you can get the same infection. That's something that there starting to take a look at. Do we have any evidence that people who are exposed to a lot of fire and say and like health care setting or something like that they're getting much more sick than other people. We don't have any. Like that yet so scientists are just starting to take a look at this question and it's based more on what we know about other diseases than anything specifically coded so. We know what other types of microbes that. Higher infectious dose can cause more severe infections in that place that they want to start. Looking for clues and seek that might be a factor here with code in nineteen president senator excited cloying. How much you're exposed to is also your viral loads after you've already got the infection how much virus is circulating in your body. Whether or not that impacts how severe the illness is this is another. Through the site witnessed that researchers wanted to take a look at the into the by measuring the viral load in active. We sick patients and comparing it to other groups to see it. You know having a higher viral load is causing a more severe illness the last. Anson that just to clarify that doesn't Meehan. Like how many viruses you encountered when you first caught the disease is it's more how much the virus has replicated with it you know. Right. Right and those two could be related if you're exposed to a higher amount might have to keep the cars to jump start to begin with it can lead two different. Results that road so. We have viral that a lot for example is with HIV obviously higher viral load can cause more severe illness and also making more infectious. Whereas if you're able to lower the viral load. You know less severe illness and also are less infectious and that's one virus from this isn't really clear correlation. I knew we talked about there being variety and people's ability to potentially get infected. With this new crap tires but they're also be. Variability in people's just in universe. Opts to the virus. Rates that's. Again another area researchers are looking at percent of a number we expect to plant there's the genetic role that we talked about already. There's people who are immune compromised for other reasons whether it's treatment for different diseases or other other underlying illnesses that could just make it. Harder for their immune system to properly now defense. And then there's also. A chance that. Having previously been exposed to I think this corona virus or a similar rotavirus. Could actually make it. Easier for the virus to infect a person causing more severe illness and the reason reconsidering this is because we've seen it. With other viruses and with dengue for example. Typically first and addicting game not so bad that if you get a second time can be really severe. And just to be clear dengue is anti gay is they mosquito borne infection. And it's it's a virus that can make you really high fever and channels and other sort of flu like symptoms but also. It's associated with the likes of your body accident some other pretty serious and Jensen and can sometimes lead to. The. Exactly yet and it's typically this secondary infection where it's all a worse response. Which is strange feeling of can't party being exposed this parents want that body has the antibodies that should be fighting off a little better tone immunity works right. But with dengue for example. There's an hour. A phenomenon called anybody dependence can't it we're basically the types of antibodies in your body has produced. And number of them. Results in them being able to buying into the virus because it does recognize them but not immediately Hewlett. And then with the virus does is takes advantage of that finding as kind of like a new heat he used to get into cells and it actually makes it even more efficient for it to infect cells. And to replicate and so sometimes are insistent can kind. Cause more problems for us rather then help us and so they can you look at that and that could be the case of corona virus. Again this is one that it's still just a high pop. That's so frustrating encounter in two actively we tend to think of antibodies as basically are body's best defense and and memory. Four. Like terrible illnesses so if you have built at the antibodies for a particular infection. You know we hope that that means that you can't. Get an illness again or at the very least you'd get it into more mild way. But this is really like taking all of our past weapons and turning them against us. Yeah and that numbers really interesting because it's a case where. Actually having a few antibodies is worse than having all because there happens sort of counter intuitive. Enhancement effect with that particular virus. You know in general. It anybody's targeting you help us build immunity but there are certain cases where kind of work against us. And I mean look at learn from reporting on this and talking experts is just how complex our immune system is it's not like. One thing that comes in fights the virus that's many many different systems all working together to try to you. Mount a defense. Learn about the virus remembered for next time create things that are staying in the body that not yet too much energy making anybody that we don't need right away it's like very complex and really sophisticated. But doesn't always work exactly the way you may hope it. What I guess they don't understand about this hypothesis is that that. Dizziness is relatively new you know it's not like anyone necessarily could've encountered this disease a year ago or ten years ago or whenever. So. Are we saying that the young people hurt getting very sick are we saying that Dave. Potentially already encountered covad. Twice it could be that you've got. You know exposed to it how to really mild or basically asymptomatic infection and then a couple weeks later experts would again. That potentially be risk factor there's also a chance that others. Corona viruses that are similar to that. Since r.'s original for example could be close enough that it would cause the same kind of effect CU were exposed to SARS. Being 2002 when it was around and those antibodies are existing your body and then Cyrus to covet 2019. Is able to take advantage of those antibodies to get this enhancement effect. Grade what about just other types of corona viruses like the common cold is there any sense Philly this could also be potentially causing this enhancement. Yes that's a good looking ahead as well it again when we don't know this enhancement is even happening at all it's just something that hit they want to take a look at because we have seen with other viruses before and there was some evidence that this was happening. With the first ours. Based on 1990 excellent business and the common cold corona viruses the resolute you know some research done there that suggested this could be happening. So that's why they're thinking well let's check concedes happening my left area that is also being investigated is an anchor piled so. In an honor our audience our microbes that this is viruses there's there's bacteria. And they can help us that they can hurt us and sometimes we found in the past certainly proves hand either Paul stern system and make it better able to find out infection. Or can hinder and make it less capable of fighting ulcers infections and that all depends on the circuit. Really specific Albania how my notes and we will work together within and without him he'd been potty. The record Bynum is paper individuals a man who plans to be different from yours. And so if we can figure out if there's certainly Grover certain set of microbes that we're together time taking her help the immune system with code in nineteen that could help. With potential treatments and also potentially. Warn people if they're more. This is also come plaques not only are we looking that. You know our own immune systems in the way our own genes sort of work -- also came in the effective of the use millions of other bikers are carrying it around us and team entered act of nineteen. Yet it's really interesting because like you know talk to these experts to do this research all the time her. All kinds. Diseases and it's only because this is such sort of an urgent outbreak that is. Getting all the attention that you know like this is there David H out this is what we do. We try to solve the mysteries and try to figure out why it is that some people have a severe reaction of the people now. And we sort of go from there and it's. Feels really intense right now because we're all seeking answers and so everything's been kind of pushed to the limit of how quickly when he solved this and so. Researchers know what they're getting they know how to do this just takes time. With Kelly thank you so much for chatting with me today and when you learn more Europeans come back on the show and give us an update. Yeah accurately test is we start getting results published I will be eager to share them with everyone yeah. Or or.

This transcript has been automatically generated and may not be 100% accurate.

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