Previous: Masks? Handwashing? Sanitizer? — How to Protect Yourself from Coronaviruses
Next: The Only Animal That Can't Breathe Oxygen



View count:1,507,527
Last sync:2022-11-27 11:00
A lot of people with coughs or fevers might be stressing out these days because they are worried that they have COVID-19. But with cold and flu season still in full swing, and the spring allergy season starting up (in the Northern Hemisphere anyway), there are plenty of other things out there that could potentially explain these symptoms.

How to care for patients with suspected coronavirus disease:

Go to to try out Brilliant’s Daily Challenges. The first 200 subscribers get 20% off an annual Premium subscription.

Hosted by: Hank Green

COVID-19 Playlist:

SciShow has a spinoff podcast! It's called SciShow Tangents. Check it out at
Support SciShow by becoming a patron on Patreon:
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:

Kevin Bealer, Jacob, Katie Marie Magnone, D.A.Noe, Charles Southerland, Eric Jensen, Christopher R Boucher, Alex Hackman, Matt Curls, Adam Brainard, Scott Satovsky Jr, Sam Buck, Ron Kakar, Chris Peters, Kevin Carpentier, Patrick D. Ashmore, Piya Shedden, Sam Lutfi, charles george, Greg

Looking for SciShow elsewhere on the internet?

Image Sources:,_1903.jpg
Thanks to Brilliant for supporting this episode of SciShow.

Go to to learn more. [♪ INTRO]. Hello everyone!

We think nothing looks different right now, but if it does, it's because we've moved our studio to my home. Because the state of Montana has told everybody to stay home for now. We're doing that, because that is what we can do to make this whole thing better.

I'll show you - I'll grab my phone right now. And show you what it looks like from my angle. This is where I sit and do my work!

And this is now the SciShow studio. We want to keep you informed, so we are going to continue bringing you SciShow News. Regular SciShow is going to continue as well, and we'll have plenty of videos about weird worms and cool stuff in outer space to keep you occupied.

Now these days, a lot of people might be getting coughs or fevers and stressing out because they're worried they have COVID-19 — the disease a lot of people are just calling “corona” or “the coronavirus.” And this is like totally understandable. The main symptoms for COVID-19 can overlap with those of common illnesses like the flu. And, at least in the northern hemisphere, it's still cold and flu season — and the spring allergy season is beginning.

Meanwhile, it can be hard to even know if you have COVID-19. Doctors want several kinds of tests to confirm. It also can take multiple tests to know for sure that you don't have it.

Even if you're tested and it comes back negative, some reports suggest that in as many as 15-30% of cases, that is a false negative — meaning you have the disease but the test didn't detect it. Which is why doctors may advise some people who get tested to self-isolate, even if they test negative. But knowing more about the symptoms of COVID-19 can give you some clues about what to do next if you start feeling crummy.

First things first: If you think you might have the coronavirus or want medical advice, you should talk to an actual doctor. I am not that. If you have acute symptoms, like trouble breathing, pause all YouTube videos and call your doctor or the emergency room.

Still, the available research does tell us a lot about what this disease generally looks like. The three main symptoms everyone's talking about are fever, dry cough, and difficulty breathing. Which makes sense, because this coronavirus is mainly a respiratory infection.

Two major review papers — one in Travel Medicine and Infectious. Disease, one in the Journal of Medical Virology — looked at symptoms across thousands of patients, mainly in China, where much of our early info is coming from. According to their analyses, close to 90% of adult patients present with a fever, and about 58-72% have a cough.

Big range there, yeah, but this comes from doing statistical analysis — it means that we're 95% certain that the true number is in between those two numbers. Only the Travel Medicine authors looked at trouble breathing, and they found that about 46% of patients had that symptom. Now, the US Centers for Disease Control lists these as the top 3 symptoms.

But according to these reviews, fatigue and muscle aches are right up there with difficulty breathing, occurring in 29-43% of patients. Kids seem to have much milder symptoms in general — for example, the review paper from the Travel Medicine group found that only 44% had fever, and just 22% had a cough. And there's some evidence that kids may actually have different symptoms — like more gastrointestinal issues, for example.

Also, it's important to remember that among both adults and kids, many cases are presymptomatic — they already have the virus, but do not yet have symptoms. We still don't quite know what that means for how those people spread the disease, but it is probably not good. Likewise, we know that there is at least a small group of adults, and probably kids, who are asymptomatic, meaning they have no symptoms at all.

In fact, a mathematical analysis published in mid-March, which looked at early cases in China and how COVID-19 then spread around the world, estimated that up to 86% of cases were mild enough to go undocumented. That doesn't necessarily mean asymptomatic — it's just not like “I need to go to the doctor” bad. But the illness, of course, can still become very severe — especially when the fever, cough, and trouble breathing combo turns into pneumonia, where the lungs become inflamed and fill with fluid.

By the way, you may keep hearing that older patients and those with preexisting conditions are more at risk, and that is true. But even younger, healthier patients can develop pneumonia, which ain't nice. The two papers found that in 15-33% of confirmed COVID-19 cases, the pneumonia can progress to acute respiratory distress syndrome, where fluid buildup leads to a severe shortness of breath that can be fatal.

That's why having enough ventilators, which help people breathe, is so important. None of these symptoms, of course, are surprising; there's a good chance you've heard all of this before. But there are the rarer symptoms, too.

The paper in Travel and Infectious Disease didn't specify numbers for these, but the other group found that about 11% of patients had a sore throat, 8% had a headache, and 6% had diarrhea. This is where you start to see how research on something as new as this coronavirus can be tricky. Both of the review papers we've been talking about only looked at studies released through the end of February.

But some of the more recent research seems to disagree about how common digestive symptoms are. In a study that followed patients through March 18, researchers in China found that of 204 hospitalized patients, half had digestive symptoms — loss of appetite, diarrhea, vomiting, or stomach pain. And even if you don't count loss of appetite as a digestive symptom, 19% of the patients still had GI issues.

The researchers note that this study has some limitations — for example, it doesn't have a huge sample size. But it's a sign that digestive symptoms may be more common than we thought based on earlier studies. Again, all of the symptoms of COVID-19 can be caused by plenty of other infections, from flu to a stomach virus to the common cold.

And in many places that don't have big outbreaks, it is still much more likely for people experiencing symptoms to be sick with something other than COVID-19. Even in New York State, which has one of the largest outbreaks in the world as of this recording, about 2/3 of tests were coming back negative as recently as last Sunday. It's also worth noting that the coronavirus doesn't usually come with itchy, watery eyes, and a runny nose or sneezing are rare.

So those symptoms — especially without a fever — might point to allergies or a cold instead. Then again, there's no reason someone couldn't have allergies or a cold and also have coronavirus. So if you've got a runny nose, that doesn't mean that you can run out and celebrate that you don't have COVID.

And there is one weird symptom that might be a sign it's COVID-19: it's losing your sense of smell. As of when we're filming this, which is March 31st, this is still very much an emerging possibility, not a for sure thing yet. But anecdotal reports started coming out a few weeks ago, and once people were paying attention to it, researchers started finding more evidence of it as a symptom.

An initial analysis, published on March 26 by researchers in Germany, cited reports that up to two thirds of patients had lost their sense of smell. And a group of British researchers report that in South Korea, 30% of otherwise mild cases had a loss of smell as their main symptom. The World Health Organization, or WHO, says it's looking into this link, but that there's not enough evidence yet to say the connection is really there.

Because even this isn't a for sure sign of coronavirus— other respiratory infections can also affect your sense of smell. What's more, there's the possibility of this bias where people start reporting symptoms that they've heard about — so the media or social media picks up on the smell thing, and then more people start to notice it and report it. Still, researchers are starting to recommend that people who lose their sense of smell should be told to self-isolate for a week or two.

They think it might help reduce the number of mild cases walking around and spreading the disease. All in all, it's tricky to diagnose people without actually testing them for COVID-19. Because even with testing capability ramping up in many countries, there are still limitations — like having enough people to administer and process those tests.

That's why the WHO has two main sets of recommendations. The first is for people who have severe symptoms, like a high fever, bad cough, or difficulty breathing. In those cases, those people should seek medical attention.

The other recommendations are for people who are otherwise healthy but have mild symptoms that could be COVID-19. In those cases, the WHO recommends people self-isolate and contact their doctor or a COVID-19 hotline for advice about getting tested. Doctors also say you can take medicines like acetaminophen or ibuprofen to help with symptoms.

Those aren't going to help the course of the disease, but they will help you feel better temporarily. There was news that went viral recently about the French Ministry of Health saying ibuprofen or similar medications could make the illness worse, but that was speculation based on an unproven theory about how infections work. It was speculation published in a reputable journal, but in science we actually need evidence, and so far there isn't any.

Some people might have issues with ibuprofen, and if that's you, you probably already know to avoid it. And none of that is specific to COVID-19. So far, the WHO hasn't recommended against taking ibuprofen.

They also have some recommendations on how. to care for someone with this disease, if hospitalization isn't an option. There's a link to that in the video description. It includes vigilant handwashing and trying to maintain at least a one-meter distance between the patient and the other members of the household.

This is a scary time, but if you have seasonal allergies, you are probably pretty familiar with how they affect you — so your old reliable allergy symptoms are nothing to panic over. If you feel like your symptoms are more unusual, stay in and call your doctor for advice. This is a good opportunity to recognize that we often sort of colloquially say like this particular disease starts with this symptom, then it progresses this way - but this is different for different people.

So there's no one symptom or one disease progression that tells you for sure that you have COVID-19. Especially because many people have it and do not have symptoms yet, or may not ever have symptoms. So limiting contact with others, whether we are symptomatic or not, is still the best thing we can do for our society and for the people on the front lines of this fight.

But researchers are working hard to change that. We'll be keeping an eye out, and you can expect upcoming SciShow News episodes to bring you more info in the coming weeks. Until then, stay safe, and thanks for watching.

If you, like me, might need things to take your mind off current events,. Why not try Brilliant's Daily Challenges? They're a fun, bite-sized way to master new STEM concepts by applying them.

You can stop by every day for a new problem to solve, relating to anything from statistics to electricity to computer science. And if you like the problem and want to learn more, there's a related course available on Brilliant that explores the same concept in greater detail. Right now, they're offering the first 200 viewers to sign up at 20% off an annual premium subscription.

And by checking them out, you're also supporting SciShow — so thanks. [♪ OUTRO].