Just one person is likely to infect between 12 and 18 people.

僅一個人就可以傳染12~18人。

That number is called a disease's "basic reproduction number," or R-naught.

這個數字被稱為疾病的「基本傳染數」或是「R0 值」。

Scientists use it to describe how contagious a disease is.

科學家用基本傳染數來說明一種疾病的傳染能力。

Zika?

茲卡病毒？

It has an R-naught of up to 6.6.

它的 R0 值高達 6.6。

Super contagious.

極具感染力。

But the seasonal flu?

而季節性流感呢？

Just a little over one.

只稍微超過 1 而已。

And Covid-19, the disease caused by the [2019 novel] coronavirus?

那麼 Covid-19 這個由冠狀病毒引起的疾病呢？

Just about two.

大約是在 2。

That difference, between the flu and COVID-19, doesn't seem so big.

流感和新冠病毒之間的區別看起來似乎不太大。

Especially when you look at them next to these really contagious diseases.

尤其是當你把它倆跟那些傳染性真正強的疾病擺在一起比較的時候。

Plus, a lot of the symptoms of the flu and COVID-19 are really similar: a fever, cough, they can even both lead to pneumonia, which is ultimately how they can both be fatal.

再加上流感和新冠病毒的許多症狀很相似：發燒及咳嗽，甚至一樣可以導致肺炎，而且最終都可能導致死亡。

So, thinking of COVID-19 and the flu as similar is a common, and frankly, understandable comparison to want to make.

所以在比較兩者之後，認為新冠病毒和流感歸類似是很普遍的，而且坦白來說，是完全可以理解的。

"This is like the flu."

「這就像流感。」

"It's a lot like the flu."

「這很像流感。」

"I'd like to believe that it's going to end up more like the flu virus."

「我想相信它最後會發展成像流感病毒一樣。」

But wait, let's go back to those R-naught numbers again.

但先等一下，讓我們再次回到 R0 值。

If the flu has an R-naught of 1.3, that means each person gets either one or two people sick.

如果流感的 R0 值為 1.3，這表示每個人都會導致 1 或 2 個人生病。

After ten rounds, that's 56 total people.

在十輪之後，染病者總共會是 56 人。

And if we run the model with COVID-19's R-naught at two, if one person with it gets two people sick, who get two people sick…

假設我們以新冠病毒的R0值為 2 模擬的話，如果一個人可以讓兩個人生病，再讓兩個人生病...

After ten rounds, that's more than 2,000 people.

經過十輪後，染病者會超過兩千人。

This does not happen with the flu.

這是流感不會發生的狀況。

Because COVID-19 is very different and understanding "How?" is crucial to understanding how dangerous it really is and why we have to take it so seriously.

因為新冠病毒非常地不一樣，而了解如何不一樣是了解其危險性是至關重要的，以及我們必須如此認真對待它的原因。

When we start to like, look for that comparison to the flu, we almost like, calm ourselves down.

當我們開始把它和流感比較時，我們讓自己幾乎完全冷靜了下來。

But unfortunately, that's not quite the right reaction here.

但很不幸地，這不是正確的反應。

Every year, the seasonal flu kills as many as 60,000 Americans.

每一年的季節性流感使多達 60,000 美國人死亡。

As of late March, COVID-19 has killed about 34,000—across the whole world.

而截至三月下旬，全球約 34,000 人死於新冠病毒。

But scientists expect that number to go up, way up.

但科學家們預期這個數字還會增加，並遠超過現在。

Tens of thousands of people a year die of the flu—but we haven't had this for a year yet.

每年都有成千上萬人死於流感，但新冠病毒的爆發還不到一年。

We've only had this for a few months.

才爆發不過短短幾個月的時間。

The trouble is coming, and we can predict it, and we can see what's coming, at least to a certain extent.

我們可以預見麻煩要來了，在某種程度上我們完全可以料到事態會如何發展。

The first really big difference between COVID-19 and the flu is how long it takes you to feel sick.

新冠病毒和流感之間的第一個大分別就是：需要多久才會感到不適。

From the moment you're infected with COVID-19, it usually takes five days before you start to feel symptoms.

從你感染新冠病毒的那一刻起，通常需要五天才會開始出現症狀。

But it can take as long as 12 or even 14 days.

但是也可能長達 12 天甚至 14 天。

This is the incubation period: the time between when you catch it, and when you first realize you're sick.

這就是潛伏期，在感染後到意識自己生病的間隔。

And scientists think you could be contagious during most of this period.

而科學家們認為在大部分的潛伏期內，你是具有傳染能力的。

The flu, by comparison, has an average incubation period of just two days.

相比之下，流感的平均潛伏期只有短短兩天的時間。

You get sick, and pretty soon you feel sick, and you know you're contagious.

你中標了，很快你就感到不舒服而且你知道自己具有傳染性。

This is what we're used to.

這是過去我們習慣處理、面對的。

But COVID-19 flips that around.

但是新冠病毒翻轉了整個局面。

You can be contagious and spreading it around for several days, and up to two weeks, before it even occurs to you that you're sick.

遠在你發現自己已經生病之前，你可能具有傳染性並到處散佈病毒持續幾天，甚至是長達兩個星期。

And that leads to the next big difference.

而這導致了下一個巨大的差異。

No human immune system had seen this virus before.

人類免疫系統從未見過這種病毒。

Nobody has a natural immunity to it.

沒有人有新冠病毒的自然免疫力。

In flu season, there's always a number of people in the population who are already immune to the flu.

在流感季節，在群眾之中總是有很多已經對流感免疫的人。

That can be because they got their flu shot, or maybe because they've already had that flu strain.

那可能是因為他們注射過流感疫苗， 或是因為他們已經得過流感。

And that limits the spread of the virus.

而這限制了病毒的傳播。

When one person is contagious with the flu, they can only spread it to people who aren't immune who can only spread it to other people who aren't immune.

當有人得流感時，他們只能將流感傳染給沒有免疫的人，而那個人也只能再傳染給沒有免疫的人。

That's why scientists and doctors urge us to get our flu shot every year.

這就是科學家和醫生督促我們每年施打流感疫苗的原因。

If enough people have immunity, they can kind of shield the virus from reaching others.

如果夠多的人具有免疫力，他們可以成為屏障使病毒無法傳播給他人。

The more immunized people, the more they can protect those that are susceptible to the virus.

而接種疫苗的人越多，他們就能保護更多那些容易受病毒感染的人。

But COVID-19 is brand new.

但是新冠病毒是個全新的病毒。

None of us have had it before, and there's no vaccine, which means nearly everyone on the planet is susceptible.

我們沒有人曾經得過也沒有疫苗，這意味著地球上幾乎每個人都是容易被感染的。

So when a contagious person, who may not even know they're infected, comes into contact with others, it can spread like wildfire.

因此當一個具有傳染性，卻不知道自己已被感染的人與他人接觸後，病毒就會像野火一樣一發不可收拾。

And then you see how much more dangerous COVID-19 can be.

而現在我們來檢視新冠病毒相較之下有多危險。

Only 2 percent of people with the flu need to be hospitalized.

只有 2％ 的流感患者需要住院。

But 20 to even 30 percent of people who test positive for COVID-19 do.

但是檢測新冠病毒為陽性的人，有 20 至 30％ 要住院治療。

And we're still learning about COVID-19's fatality rate, but scientists think it's somewhere between 1 and 3 percent.

我們仍在研究新冠病毒的致死率，但科學​​家認為致死率介於 1 至 3％之間。

But the flu's rate is even lower: 0.1 percent.

但流感的致死率卻是更低：0.1％。

And that's a disease that can kill 60,000 people a year in the U.S. alone.

而流感是一種在美國僅一年就可以殺死 60,000 人的疾病。

That's what Dr. Anthony Fauci, the US's leading infectious disease expert, tried to clear up to Congress.

以下是美國頂尖的傳染病專家 Anthony Fauci 博士在國會上的說明。

"People always say, well, the flu does this, the flu does that. The flu has a mortality of 0.1 percent. This has a mortality of ten times that. This is a really serious problem that we have to take seriously."

「人們總是說，流感怎麼樣。流感的死亡率是 0.1％，而新冠病毒的死亡率是十倍。這是一個我們必須認真去對待的嚴重問題。」

And he's just talking about the average across all age groups.

而他只是說明全年齡層的死亡率平均值。

For older people, or people with compromised immune systems, it can be way higher.

對於老年人或免疫系統不健全的群眾來說死亡率可能更高。

And that's especially scary when you remember all the other things that are different about COVID-19: the infectiousness, how hard it is to know that you have it, how susceptible we all are to it.

而所有關於新冠病毒的不同之處更令人恐懼 ：傳染性、有多難知道自己已經中標、我們有多容易被傳染。

Estimates vary, but some scientists have warned that between 20 and 60 percent of the world's population could become infected with the virus.

評估各有不同，但有一些科學家警告佔世界 20 至 60％ 的人口可能會感染該病毒。

Because COVID-19 has no cure and no vaccine, the only defense we have against it is social.

由於新冠病毒還沒有解藥和疫苗，我們對此的唯一防禦措施是社交。

We can take ourselves out of the chain—not with immunity, but with social distancing.

我們可以透過社交距離而不是免疫力來擺脫傳播鏈。

Just physically not being around anyone, and staying home as much as possible.

只要不與任何人有肢體上接觸，並且盡可能地待在家裡。

But that only works if each of us takes it seriously, which is why comparing it to the flu, while understandable, is not helpful.

但這只有在我們每個人都認真執行的情況下才會產生效果，這就是將其與流感進行比較，雖然可以理解但卻完全沒有幫助的原因。

It's natural to want to find a comparison, to want to make this seem small.

想找個東西比較讓事態看起來不嚴重是很自然的事情。

When we use the flu as the backdrop, it almost numbs us, or it can numb us, and make us maybe even feel better about the current situation.

當我們以流感作為參照時，會讓我們幾乎麻木或者可能使我們麻木，而讓我們對目前的情況感覺好一些。

Because the current situation is bad so now is not the time to be numb.

但正因為目前的狀況很糟糕，因此現在不是麻木的時候。

We need to be vigilant, and then use our vigilance for useful actions.

我們需要保持警惕，並進一步利用警覺性採取有用的行動。