But arguably, the most important part is here: in the human trials.

但當中可以說是最重要的部分則在這裡：人體試驗。

Where the vaccine is tested on real people, in three main phases, starting with just a small group of people, and ultimately testing a group of thousands.

疫苗會在此被注射至真人身上測試，其中主要分三個階段。先從一小群人開始，最後讓已數千人為單位的群體測試。

This is where scientists confirm the effectiveness and safety of the vaccine on a large scale. Before that, scientists scrutinize its effectiveness.

科學家們在這裡大規模地確認疫苗的有效性和安全性。而在此之前，科學家們會仔細研究其有效性。

But before any of that, a vaccine first has to pass this crucial phase, where scientists study the side effects.

但在這所有步驟之前，疫苗必須通過這個關鍵的第一階段，讓科學家先多加研究其副作用。

In a trial you call it "adverse events." But that doesn't.... that's kind of overstating it.

在試驗中我們稱之為「不良事件」。但它其實不會⋯ 這個名字有點言過其實了。

Dr. Kirsten Lyke led a Phase I trial for the Covid-19 vaccine made by Pfizer and BioNTech.

Kirsten Lyke 博士主導了了輝瑞和 BioNTech 公司所生產的 Covid-19 疫苗的一期試驗。

She says side effects are a possibility with any vaccine.

她說，任何疫苗都有可能產生副作用。

In general, it's nothing to fear. It's our own immune systems kicking in and doing what it's supposed to do.

一般來說，這沒什麼好害怕的。這代表我們的免疫系統開始運作，並做了它該做的事。

The most common flu vaccine this year, for example, comes with a chance for many normal side effects: pain, fatigue, headaches.

比如在今年最常見的流感疫苗中，伴隨著許多正常的副作用，例如疼痛、疲勞、頭痛等等。

But many of the new Covid-19 vaccines are more likely to cause these kinds of side effects than you might be used to, particularly after the second dose.

但很多新的 Covid-19 疫苗比你過去可能習慣的疫苗更容易引起這類副作用，特別是在接種第二劑之後。

Most people will feel a little pain in their arm. Many will be tired and get headaches.

大多數人都會感覺到手臂有些疼痛。很多人會感到疲憊與頭痛。

I mean, obviously, having no side effects is desirable.

我的意思是，很顯然沒有任何副作用是最好的。

But I think with the spike protein of the coronavirus, it really does elicit some side effects.

但我認為由於冠狀病毒穗蛋白的特性，它確實更容易引起一些副作用。

But that's totally normal.

但這是完全正常的。

And once you understand why vaccine side effects happen, you might actually be happy to get them.

而當你瞭解了疫苗副作用發生的原因後，你可能反而會因為得到副作用而感到高興。

First, we have to talk about this: your immune system, which is a huge network of different cells and proteins in your body.

首先，我們得先說明一下：你的免疫系統是一個在你體內巨大的網路，以各種不同的細胞和蛋白質組成。

You've got things like white blood cells that fight the invading virus or bacteria, communication cells that organize the response, and antibodies that search for and identify the enemy.

你有像是白血球這樣的單位來對抗入侵的病毒或細菌、用來組織反應的通信細胞，以及搜索和識別敵人的抗體。

When, say, a virus attacks your body, your immune system attacks back.

在某些情況，例如當病毒攻擊你的身體時，你的免疫系統就會反擊。

Your body increases blood flow to get more of these battle cells in circulation.

你的身體會增加血流量，讓更多的這些戰鬥細胞進入準備就位。

Your temperature might go up, too, as one of the tactics your body has to help kill the invaders.

你的體溫可能也會上升，作為你的身體幫助殺死入侵者的戰術之一。

And after your white blood cells destroy the virus, they produce antibodies that will identify the virus should it reappear in the future, and remember how to fight it.

而在你的白血球消滅病毒之後，它們所產生的抗體將能在病毒未來再次出現時認出它，並記得如何對抗它。

They're how you gain immunity.

抗體就是你獲得免疫力的方法。

This response is actually what gives you a lot of the symptoms you feel when you catch, for example, the common cold.

這種反應其實就是你會在得到例如一般感冒等疾病時，會感受到的症狀。

But the cold virus doesn't give you a fever, or a runny nose, or body aches — your immune system does while fighting the virus.

但感冒病毒並不會直接讓你發燒、流鼻水、身體痠痛－這些其實是你的免疫系統在對抗病毒的同時所作出的反應。

And triggering this system, without actually getting you sick, is how vaccines work.

而疫苗發揮效用的方式，就是在不會讓你真的得病的同時，觸發這個系統。

Most vaccines are made up of a weakened or dead pathogen, or a portion of one.

大多數疫苗都是由弱化或死亡的病原體，或其中的一部分所組成的。

Or, in some of the new Covid-19 vaccines, the genetic code of a portion of one, either in the form of DNA, or what's called messenger RNA, along with minor ingredients to keep it stable.

或者在一些新的 Covid-19 疫苗中，則是由其中一部分的遺傳密碼，可能是以 DNA 或是所謂的信使 RNA 的形式，加上一些其它使疫苗穩定的次要成分所組成的。

It's harmless, but when your immune system detects it, it responds just like it's a real danger.

疫苗是無害的，但當免疫系統檢測到它時，便會像是偵測到真正危險那樣地進行反應。

It attacks the intruder, and creates those memory antibodies to be able to fight it again in the future.

它會開始攻擊入侵者，並產生那些記憶抗體以便將來能夠再次迎擊病原體。

Vaccines are designed to give you the same immunity as if you would fought off the real virus, and some of the new Covid-19 ones do this particularly well.

疫苗就是設計來讓你的身體進行一場彷彿與真正病毒交手過的演習，而某些新的 Covid-19 疫苗特別擅長這點。

The messenger RNA vaccines are quite good at stimulating your immune system. That's why you have ninety-five percent efficacy.

信使 RNA 疫苗相當擅長刺激你的免疫系統。這也是為什麼接種後能達到百分之九十五的抗病毒能力。

That's right — a 95% chance of being protected against Covid-19. That makes them some of the most effective vaccines.

沒錯，有 95% 的機率可以抵禦 Covid-19 病毒。這使得它們成為最有效的疫苗之一。

But that also means they're really good at activating your immune system.

但這也意味著它們會對免疫系統造成相當刺激。

Which means your body will increase blood flow to where that vaccine is, which is why pain at the injection site is so common.

也就是說你的身體會指示血液更多地流向接踵的部位，而這也是為什麼通常接種的部位會格外疼痛的原因。

Your body might even think, "Better turn up the heat!", and then you get a fever, or the chills.

你的身體甚至可能會想：「把體溫提升更高一點吧！」，於是你便會開始發燒或者發冷。

So experts emphasize that we should look at most side effects as a good thing: It means the vaccine is working.

因此專家強調，我們應該把大部分副作用看成是好事：因為這代表著疫苗正在產生效用。

I have a friend, actually, who participated in one of the Pfizer trials, the early trials, and, you know, so he could have gotten either placebo or vaccine.

我有一個朋友，他參加了輝瑞的一個早期試驗，所以他接種到的可能是安慰劑，也可能是疫苗。

After the second dose, the next day he woke up and he had... he was sort of fatigued and he had low grade fever. And he looked at his wife and said, "Yes!! I got the vaccine!!"

在打了第二劑之後，隔天早上醒來他覺得自己有點疲勞，而且還發了低燒。他於是看著妻子說到：「讚啦！我打到的是疫苗！」

See, that's the right attitude.

看，這才是正確的態度。

When we talk about these common reactions to vaccines, like fever and fatigue, we're mostly talking about the mild-to-moderate ones.

當我們說到這些疫苗的常見反應，比如發燒、疲勞等等，我們主要說的是輕度到中度的症狀。

These are the lowest of the side effect categories that health regulators use, the kind you get over in a day or two.

這些都是衛生監管部門所使用的最低的副作用類別，也就是一兩天就會過去的那種。

Then there's severe side effects — the type that might make you call in sick to work or call a doctor.

而另外還有嚴重的副作用，那種可能讓你請病假，或者跟醫生掛號的那種。

These were rare in the clinical trials for the first two studied vaccines to become available, with the exception of some severe fatigue and muscle pain on the second dose.

在最快上市的兩疫苗的臨床試驗中，這些嚴重的副作用相當罕見，只有在施打第二劑時有部分嚴重疲勞與肌肉疼痛的少數案例。

And that's because if these vaccines were dangerous, they'd never reach the public in the first place.

那是因為如果這些疫苗真的那麼危險，它們打從一開始便不會面世。

We really don't accept any sort of permanent, serious harm from a vaccine, nor should we.

我們並不會因為任何一種疫苗而接受到永久、嚴重的傷害，也不應該接受。

News stories that imply otherwise can be scary, but they get more attention than they probably deserve.

許多不這麼暗示的新聞看似駭人聽聞，但或許它們博取到的關注有些過度了。

Like this one, about a serious allergic reaction... in someone with a history of serious allergic reactions.

像是這篇新聞講述了一個嚴重過敏的案例⋯但當事人本身就有著嚴重過敏反應的病史。

Or this one, about someone dying after getting a second dose of the vaccine... when, it turned out, other factors had caused his death.

或者這篇新聞，說了有人在打了第二劑疫苗之後死亡⋯結果最後發現，其實是其他的因素導致了他的死亡。

In fact, no deaths have been reported from the millions of doses that have been given out.

事實上，在已施打的數百萬劑疫苗中，並沒有任何的死亡案例。

And the controlled studies with thousands of people found the same thing: No deaths from the vaccine.

而數千人的對照研究也引導出了一樣的結果：沒有因為疫苗而死亡。

But maybe more importantly, the studies also recorded zero deaths from Covid-19, and zero hospitalizations from Covid-19.

但也許更重要的是，這些研究還記錄了沒有人因為 Covid-19 而死，也沒有人因 Covid-19 而住院。

These vaccines aren't just safe — they're life savers.

這些疫苗不僅安全，而且還是救命稻草。

You should be skeptical of anything you put in your body, including vaccines.

你確實應該對任何放進你身體裡的東西持懷疑態度，包括疫苗也是。

But once you've seen the data, and you see that there wasn't a serious side effect before approval, and hasn't been a serious side effect post-approval, then I think you should be convinced.

但在看到數據之後，看到疫苗在核准前並沒有嚴重的副作用，看到核准後到目前為止也都還沒有出現過嚴重的副作用，那麼我想你應該要對它的安全性有信心。

Basically, you want to reduce where the virus can go.

基本上，我們希望能限制病毒傳播的途徑。

And if you immunize as many people as possible, that pool of people that it can transmit to becomes less and less and less and less.

而只要讓盡可能多的人免疫，病毒能感染的人群術也會越變越少。

Vaccines are the way out of the Covid-19 pandemic.

疫苗是 Covid-19 疫情的最終解藥。

And, like with all vaccines, many of us who get it will also feel a little... meh... for a day or two.

就像所有的疫苗一樣，我們中的很多人接種後的一兩天也會覺得有點... 不太舒服。

But the scientists who have studied these vaccines — who have seen the side effects — are some of the most eager to get it.

但是，研究這些疫苗並實際看到副作用案例的科學家們，反而是最想得到副作用的人。

I couldn't wait to get this vaccine, are you kidding me? I mean, two doses of vaccine gives me a 95% chance of being protected.

我根本迫不及待地想打這個疫苗，別鬧了好嗎？我的意思是，只要打兩劑就能讓我有 95% 的免疫機率欸。

We would be the first ones to not want to take it if we felt it was unsafe, right?

如果我們自己都覺得不安全了，我們肯定不會想接種對吧？

So, um, take it from your friendly vaccine person!

所以，請接受你的友好疫苗從業人員的建議吧！