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Do you feel that chill in the air?
你感受到空气中的寒冷了吗？
In a lot of places around the world, including North America and Europe，
这是一段"美好"的时光，我们称之为“流感季”
it's that a lovely time of year known as flu seaon.
它出现于世界上的许多地方，包括北美和欧洲。
And each year, we try to fight flu season with the influenza vaccine.
每年 我们都打流感疫苗来抵抗流感
Every season is kind of a whole new battle for researchers, because flu viruses evolve quickly.
每个流感季对医学研究者而言都是一次全新的战斗 因为流感病毒进化的非常快
This year is no different.
今年也不例外
The fact that there's a flu season means doctors and healthcare organizations can prepare for it.
事实上 流感季的存在 意味着医生和医疗机构 可以为此进行准备
But why is there a flu season at all? Why isn't there just flu flying around everywhere all year?
但为什么会有流感季呢？为什么流感不是全年都有而且遍布全世界呢？
Well, there are actually /two/ flu seasons every year,
实际上 每年有两个流感季
because the Northern hemisphere and the Southern hemisphere experience winters at opposite times of year.
因为北半球和南半球的冬天刚好在一年相反的时间里
So here in the United States, for example, flu season lasts from about November through March.
因此例如 美国的流感季 大概从十一月开始到三月
And countries in the Southern hemisphere typically face the flu between May and September.
而南半球国家通常在五月到九月会遭遇流感
The flu virus /does/ circulate year round, but the number of cases rapidly increases during these peak months,
流感病毒确实会流行整年 但是患病数量在这几个月上升快速达到顶峰
giving influenza its own holiday season to celebrate.
给流行性感冒腾出了一段狂欢假日
Research suggests that winter months are ideal for influenza transmission
研究显示 流感传播的最佳时间就是在
because they bring a combination of cool air and low humidity.
促使冷空气和低湿度相结合的冬天的那几个月里
Influenza virus is transmitted through droplets from a sneeze or cough that are carried in the air.
从而在空气中传播 这种来自于一个喷嚏或咳嗽并留存在空气中唾液水珠为媒介进行传播
When temperature and humidity are low, these droplets can fly easily through the air without much resistance.
在气温和湿度都很低的情况下 这些水珠可以轻而易举 没有过多阻力的游荡在空气中
But in warmer and more humid climates, the extra moisture in the air makes the droplets bigger and heavier,
但在暖和和潮湿的气候里 空气中其它水分 使得水珠又大又重
and therefore more likely to fall out of suspension in the air.
因而更容易从悬浮的状态掉落
So the virus can't travel very far.
这样病毒就没法传播太远
And of course, cooler temperatures also mean people tend to stay indoors,
当然 低气温环境也意味着人们会更愿意待在室内
increasing the number of potential bodies in an enclosed space for the virus to infect.
这就增加了病毒在密闭空间传染更多潜在受体的机会
Makes sense, right?
这合乎逻辑 对吧？
But even if the influenza keeps going from one hemisphere to the next, why do we need a different vaccine every year?
但既然流感病毒从一个半球传播到另一个半球 为什么每年仍然需要不同的疫苗？
Each flu season is unique, because the influenza virus mutates from year to year.
每个流感季都是独特的 流感病毒每年都在变异
There are three major types of influenza: labeled A, B, and C.
流感病毒主要有三大类 即A类 B类和C类
And influenza A viruses are further categorized into subtypes, depending on the two proteins that coat their outer shells.
其中A类流感病毒进一步细化为亚型 这些亚型的分类取决于外壳依附的蛋白质类型
There are the HA, or hemagglutinin [hee-muh-glue-tuh-nin] proteins,
它们是HA血凝素蛋白
and the NA, or neuraminidase [new-rah-min-uh-dace] proteins.
和NA 神经氨酶蛋白
These proteins act like beacons to a host cell, tricking the cell into letting the virus attach and infect it.
这些蛋白质好比灯塔 指引流感病毒进入寄主细胞 迷惑寄主细胞让病毒进入并感染寄主细胞
There are different subtypes of these proteins,
这些蛋白质有不同的亚型
H1 through H18 for the hemagglutinins and N1 through N11 for neuraminidase.
血凝素蛋白从H1型到H18型 神经氨酶蛋白从N1性到N11型
So, the different combinations are why we talk about flu strains in terms of, say, H1N1 or H3N2.
这些不同亚型的结合就是我们对于它们的不同称呼 例如H1N1或者H3N2
But these HA and NA proteins mutate very easily, through a process called antigenic drift.
但是这些HA和NA蛋白非常容易变异 我们称这个过程为抗原性漂移
These small changes don't alter the virus very much, but after some time,
这些小改变不会马上改变病毒 但经过一段时间
the changes accumulate, and can result in a new strain of virus that acts in completely different ways than the original did.
转变逐渐升级 就可以产生一个新的病原体家族 这种病原体家族和之前的表现完全不同
And sometimes, in rarer cases, genetic mutations in the virus can cause big, dangerous changes.
甚至有些时候 在极少数的情况下 病毒的基因变异还会带来巨大且危险的改变
This is called antigenic /shift/, and it can result in a brand new combination of genes that make the virus much more infectious.
称其为抗原性转变 它会导致一种全新的基因结合 使得病毒更易传染
You might remember the antigenic shift that happened back in 2009.
你们也许还记得2009年发生的那次抗原性转变
That’s what created swine flu.
猪流感就是这么来的
So, with different viruses mutating all the time,
由于不同病毒的持续不断地变异
how do we know which strains are the one we should get vaccinated against this winter?
我们怎么知道哪些病毒种类是我们这个冬天需要接种疫苗的呢？
Four strains are selected based on data collected throughout the year by health organizations
医疗卫生组织全年监测流感病毒在世界各国的活动情况
monitoring flu activity in various countries around the globe.
选出了四类流感病毒
They report it to a network run by the World Health Organization,
他们发布在世界卫生组织的网站上
which then compiles the data to predict which strains will likely be circulating during peak seasons
这个网站汇总了数据来预测哪些病毒种类将有可能在流感季传播
and come up with recommendations for that year's vaccines.
并给出了那年该打什么疫苗的建议
Since the Northern Hemisphere and Southern Hemisphere tag-team winters,
南北半球组成联合对抗冬季流感
usually the data collected during /one/ flu season will help inform the /other/ hemisphere about which
通常一个半球一个流感季收集的数据会通知另一个半球
strains are doing the most damage, and if the vaccines were effective or not.
告知他们那些流感类型最具伤害性 针对这些病毒的疫苗是否有效
Flu vaccines are actually developed /months/ before peak season starts, to allow time for them to be made and tested.
流感疫苗通常在流感季到来的前几个月就研发好了 以便留出时间来生产和试验
But that means that sometimes the viruses that are circulating change while vaccines are being produced,
但这也就意味着病毒可能在疫苗研制过程中改变类型
so the vaccines might end up not being as effective.
以至于疫苗到最后无法发挥效果
So, what strains are we up against this year?
那么，今年我们需要防御什么病毒呢？
There’s A/California/7/2009 (H1N1)pdm09-like virus, whose really long name comes from things like its type,
它是A/California/7/2009(H1N1)pdm09-like病毒，它长长的名字来自它的类型
where and when it was first isolated, and the subtype of its HA and NA proteins.
它何时何地被分离出来，以及它HA和NA蛋白的类型
It's an influenza A virus isolated from California that’s closely related to the strain that caused the 2009 H1N1 pandemic.
这是一种流行性A类病毒，分离于加利福尼亚 与导致2009年流行性感冒的H1N1病毒联系密切
Then there's A/Hong Kong/4801/2014 (H3N2)-like virus...
然后就是A/香港/4801/2014(H3N2)-like病毒
And a strain called B/Brisbane/60/2008-like virus which comes from a line of B viruses from Victoria, Australia.
以及 B/Brisbane/60/2008-like病毒 它源于来自澳大利亚维多利亚的B类病毒
It gets a slightly shorter name because influenza B viruses aren't categorized by subtype.
它有一个略短的名字是因为B类病毒不以类型命名
In the quadrivalent vaccines like the nasal spray version, a fourth strain is included
四价染色体疫苗如鼻部喷雾疫苗可以应用于四分之一的病毒
and is called B/Phuket/3073/2013-like virus descended from the Yamagata, Japan lineage of B viruses.
以及来源于日本山形隶属于B类病毒的 B/Phuket/3073/2013-like病毒
So just like spring, summer, fall, and winter, flu season is an inevitable season that comes back year after year.
所以就像春夏秋冬的轮回一样 流感季也会不可避免的年复一年的出现
But scientists do their best to fight it by working year round to keep us up-to-date and protected from the ever-changing flu.
但是科学家尽他们最大的努力通过他们每年的工作 为我们更新对病毒的了解，保护我们免受持续改变的病毒的感染
So if it's almost winter where you live, go get your flu shot if you haven't yet,
如果你居住的地方快要入冬你还没有注射疫苗的话，尽快去注射
and brace yourself, flu season is coming.
振奋精神，流感季就要来了
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感谢你们观看SciShow的这个视频 这个视频由Patreon上的赞助者赞助。
If you want to help support this show, just go to patreon.com/scishow.
如果你们想要支持这个节目，请访问patreon.com/ scishow
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不要忘记到youtube.com/scishow为我们点赞
