Thanks to Brilliant for supporting this episode of SciShow.

Go to Brilliant.org/SciShow to learn more. {♫Intro♫}. This video was filmed on March 3 2020.

If we have a more up-to-date version of it, it will be linked at the top of the description, and right up there. Let's go over some terminology to start. SARS-CoV-2 is a virus, specifically it is a new kind of Coronavirus that appeared suddenly in late 2019 in the city of Wuhan, China.

Coronaviruses are common, you have likely had a coronavirus lots of times, it's one kind of virus that causes the common cold. But they can also cause SARS and MERS, two diseases that have very high case mortality rates. They're very dangerous, and the disease that SARS-CoV-2 causes has been named COVID-19 short for coronavirus disease 2019.

This disease spread very quickly in China at first, but new cases there are slowing, and now the majority of new cases are outside China. This raises the question...do we have a pandemic on our hands? And the answer, yes, maybe, also no, and also it doesn't really matter and it actually matters a lot.

So...that's why this video is here. First of all, “Pandemic” sounds like an official term, but there aren't super hard rules or numbers for when it can or should be used. In general, we use the term epidemic to describe a sudden, unexpected increase in cases of a disease in a particular region.

A pandemic, on the other hand, is sudden, unexpected worldwide spread of a disease. Why does the difference between those things matter? Well, it's not just whether we get to use a scarier word in the headlines… there's also a difference in how we respond.

Epidemics you contain. Pandemics you can only mitigate. So, then how do we decide when something is a pandemic?

Researchers have said they'd need to see evidence of sustained, domestic transmission in at least one more region outside of the Pacific region that includes China, Japan, and South Korea before using the term “pandemic”. So the question is whether these cases outside the Pacific are spreading on their own. Not just new arrivals, but new spread.

And while we didn't see any evidence of that in the early months of the COVID-19 outbreak, we now have seen cases that aren't directly linked to either travel, or exposure to people who've traveled. Instead, it looks like it might be what's known as community spread. Community spread, or community cases, are essentially when the source of the infection is unknown.

In this case, that would mean people who haven't been to China and also have't been in direct contact with someone who was recently in China are getting sick. It's spreading from person to person in their own community via droplets from coughing or sneezing or just, talking loudly. As of February 29th, three states in the US have reported community-acquired cases:.

California, Oregon, and Washington. And a preliminary genetic analysis of the virus, sampled from two separate patients in Washington state, suggests that the virus was quietly spreading there for a while. The virus in the two patients had a particular genetic signature that only a small fraction of samples from China had.

If the two cases were both new introductions from abroad, it would be unlikely that they both had that signature. That suggests that there has been sustained transmission in Washington state for several weeks -- though we'd need to find the sick people who did that transmission to confirm this. It seems likely that there are more cases than outbreak responders are aware of, probably because those people simply aren't sick enough to go to the doctor.

So does this make this a pandemic? Again, there's not a hard and fast rule, but remember we'd need to see not just domestic transmission, but sustained transmission. So is that happening?

Well, many experts and scientists say yes, but, as of this recording, the WHO (World Health Organization) has chosen not to use the word pandemic. And it so happens that the WHO is having meetings between when we're filming this and when you're seeing it. They're the ones who get to say, although even if they say it, it's not a formal term -- just their assessment of things.

The formal use of the word “pandemic” was actually retired in 2009! If they decide at those meetings that they've seen what they're looking for, they may switch from their current policy of trying to contain the disease, to naming it a pandemic and switching to a strategy of mitigating the effects. They're looking for sustained, community-acquired transmission – that is, many, many cases where no one knows how someone got sick.

Now this might seem like splitting hairs, but there are reasons why they might be shy about making this call. No one responds to news like “there's a pandemic” lightly, and they get that. As for why we ended up in this situation in the first place, we do have some ideas about why COVID-19 has been able to spread.

As we mentioned, it's spread from person to person in droplets when a sick person coughs or sneezes. It's also been suggested that a number of cases are being spread by folks without any symptoms at all. That's called asymptomatic transmission.

But on Tuesday, the WHO said that, at least in China, only one percent of reported cases had no symptoms - and most of those developed symptoms within days. So it looks like asymptomatic transmission is really rare, and that's unlikely to be the main driver of new cases, which is very good news. Pandemic or no pandemic, it's important to remember that this designation has nothing to do with how deadly a disease is.

The term only describes where the disease is spreading. It doesn't tell you anything else. And we're not really sure what the mortality rate of COVID-19 is.

It's changing so fast it's hard to even pick a number to cite. For one thing, it's been different so far in China than in the rest of the world, and different in some parts of China than in other parts of China. For another, the actual rate might be much lower, since mild cases may very well be going unrecognized.

You may have heard a figure around two percent cited in the news, and that's backed up by the published literature so far, but it's probably not going to be the number we have when the dust settles. And the number's gonna be very different in places with more robust healthcare systems than in places that don't have lots of respirators. We're planning a whole other episode for you on how we understand and compare fatality rates, so keep an eye out for that.

In the end, whether something's an epidemic or pandemic may have as much to do with our response to the disease as the disease itself. If it's an epidemic, the nation or region where it's happening may try to contain it and prevent it from getting out. But with a pandemic, the focus may be more on mitigation efforts, like surveillance, treatment, and protecting vulnerable populations.

They may also focus on slowing the spread of the disease through what's called social distancing: things like dismissing school or postponing mass gatherings, rather than just trying to keep it out of the community. And there are also things we as individuals can do to help prevent the spread of the disease. People should be aware of the symptoms of this disease, which include fever, dry cough, and tiredness.

Those are the main COVID specific things to watch out for. People might also get aches and pains, a sore throat, a runny or congested nose… and I realize now I'm just listing symptoms of a cold or flu! That's why it's really important to contact your doctor if you start having any difficulty breathing -- which is more indicative of this disease.

And when I say contact a doctor,. I mean call them, don't go in to sit in a waiting room with a bunch of strangers. The US Centers for Disease Control recommends avoiding touching your face, avoiding close contact with people who are sick, and staying home if you yourself are sick.

You should also wash your hands with soap and water for at least 20 seconds. That's not just some empty platitude. Coronaviruses are surrounded by an envelope of oily material.

And soap is really, really good at disrupting and dissolving oily stuff. So washing your hands with soap and water for 20 seconds -- about the time it takes to sing Twinkle, Twinkle, Little Star, or the chorus from Toto's “Africa,” whichever you prefer -- is a genuinely effective way of destroying virus particles. And you should also get your flu shot.

We mean this. Now, the flu shot isn't gonna protect you from COVID-19, but the flu and COVID-19 have similar symptoms. Which means one could be confused for the other, placing an extra burden of testing and treatment on health providers.

Plus, you're less likely to get the flu, and the flu sucks. Also if you do get it, it'll probably be less severe, meaning you're less likely to need treatment from a potentially overworked healthcare system. They also want people to stop buying face masks.

Surgical masks are good at keeping your stuff in, not necessarily the world out. So unless you're a healthcare worker or already sick, or you are in a specific situation where your doctor has recommended a mask, they won't do much. And we should leave them for the people who need them.

In sum, it's understandable that the word “pandemic” is being thrown around, whether. COVID-19 is one by definition or assignation by the WHO or not. It's okay to be concerned.

After all, events like this are uncertain, and we can give you some facts here on SciShow, but we can't eliminate that uncertainty. There are many people who've been affected, families who've lost loved ones and we should keep them in our hearts. But when you see the whole story from a thousand feet up, it's relatively mild compared to what we'd feared.

There are clear things we can all do to reduce the risk of transmission, both for our own benefit and for those around us;. And there are a lot of smart people working really hard to make this better.

Outro: Thanks for watching this episode of SciShow. News. We really hope it's helped you understand a complex and rapidly changing situation. And it's been brought to you in part by Brilliant.org.

They want to help us all get smarter day by day -- and for that, they have their daily challenges. From statistics to electricity to computer science, these questions will give you a new way to challenge yourself every day, and learn how we understand the world around us. Each problem comes with illustrations, animations, or interactive visualizations, and all the context you need to solve the problem yourself.

What's more, you can access each day's challenges for free -- though Premium members get access to the full archive. And the first 200 people to sign up at Brilliant.org/SciShow will get 20% off an annual Premium subscription. Just remember -- by checking them out, you're helping support us so we can make videos like this.

So thanks. {♫Outro♫}.