为什么老年人受到Covid-19的威胁更大
掩盖是减少COVID-19感染风险的一种方法。
亚历克斯·布兰登/盖蒂图片社

唐纳德·特朗普总统宣布 他的COVID-19测试阳性 is especially concerning because of his age.由于他的年龄而特别令人担忧。 At 74 years old, Trump is solidly within an age group that's been hit hard during the coronavirus pandemic.特朗普现年XNUMX岁,处在一个在冠状病毒大流行中遭受重创的年龄组中。

People of all ages can get sick from SARS-CoV-2, the virus that causes COVID-19.所有年龄段的人都可以从SARS-CoV-XNUMX(引起COVID-XNUMX的病毒)中生病。 But the severity of the illness tends to worsen the older the patient is.但是这种疾病的严重性往往使患者年龄变大。 Through the end of September,到XNUMX月底, 79%的COVID-19死亡 在美国已有65岁以上的患者。这些统计数据是 大致相同 在世界各国.

What is it that puts older people at increased risk from viruses like SARS-CoV-2?是什么使老年人更容易受到SARS-CoV-XNUMX等病毒的威胁? Scientists think it's primarily due to changes in the human immune system as we age.科学家认为,这主要是由于人类衰老过程中人体免疫系统的变化。

人体抵抗病毒感染的工具

As you go about your life, your body is constantly bombarded by pathogens – the bacteria, fungi and viruses that can make you sick.在您的生活中,您的身体会不断受到病原体的袭击,这些病原体可能使您生病,而细菌,真菌和病毒会给您造成伤害。 A human body is a great place for these organisms to grow and thrive, providing a nice warm environment with plenty of nutrients.人体是这些生物得以生长和繁衍的好地方,提供了一个充满营养的良好温暖环境。


内在自我订阅图形


That's where your immune system comes in. It's your body's defense system against these kinds of invaders.那就是您的免疫系统进入的地方。这是您身体抵抗这些入侵者的防御系统。 Before you're even born, your body starts producing specialized B-cells and T-cells – types of white blood cells that can recognize pathogens and help block their growth.在您出生之前,您的身体就开始产生专门的B细胞和T细胞-可以识别病原体并帮助阻止其生长的白细胞。

T细胞通过识别感染的细胞并杀死它们来发挥作用。 Together they make up what scientists call your “adaptive” immune system.它们共同构成了科学家所谓的“自适应”免疫系统。

Maybe your physician has checked your white blood cell levels.也许您的医师检查了您的白细胞水平。 That's a measurement of whether you have more B-cells and T-cells in your blood than usual, presumably because they're fighting infection.这是对您的血液中B细胞和T细胞是否比平时更多的一种度量,大概是因为它们正在抵抗感染。

When you're very young, you don't have a lot of these B- or T-cells.当您很小的时候,这些B细胞或T细胞就不会很多。 It can be a challenge for your body to control infection because it's simply not used to the job.控制您的身体可能是一个挑战,因为它根本不习惯工作。 As you mature, your adaptive immune system learns to recognize pathogens and handle these constant invasions, allowing you to fight off infection quickly and effectively.随着年龄的增长,您的适应性免疫系统将学会识别病原体并处理这些不断发生的入侵,从而使您能够快速有效地抵抗感染。

While white blood cells are powerful people-protectors, they're not enough on their own.尽管白细胞是强大的保护人的物质,但单靠它们还不够。 Luckily, your immune system has another layer, what's called your幸运的是,您的免疫系统还有另外一层,那就是您的 “先天”免疫反应。 Every cell has its own little immune system that allows it to directly respond to pathogens quicker than it takes to mobilize the adaptive response.每个细胞都有其自身的免疫系统,因此其对病原体的直接反应要比调动适应性反应更快。

The innate immune response is tuned to pounce on types of molecules that are commonly found on bacteria and viruses but not in human cells.调节先天免疫反应,以突触在细菌和病毒上常见但在人类细胞中不常见的分子类型。 When a cell detects these invader molecules, it triggers production of an antiviral interferon protein.当细胞检测到这些入侵分子时,就会触发抗病毒干扰素蛋白的产生。 Interferon triggers the infected cell to die, limiting infection.干扰素触发受感染的细胞死亡,从而限制了感染。

另一种类型的先天免疫细胞,称为单核细胞,起着一种细胞跳动的作用,摆脱了它发现的任何感染细胞,并发出了适应性免疫应答转变为齿轮的信号。

先天性和适应性免疫系统可以一起充当微调的机器,以检测和清除病原体。

免疫系统较弱

当病原体入侵时,疾病和健康之间的区别是病原体可以在您体内传播的速度与免疫反应在不引起过多附带损害的情况下可以反应的速度之间的竞赛。

随着人们年龄的增长,其先天性和适应性免疫反应发生变化,从而改变了这种平衡。

老年人的单核细胞 产生较少的干扰素 in response to viral infections.应对病毒感染。 They have a harder time killing infected cells and signaling the adaptive immune response to get going.他们很难杀死被感染的细胞,并发出适应性免疫反应以继续前进。

通常在衰老过程中发生的个人低度慢性炎症也可能 减弱先天性和适应性免疫反应的能力 to react to pathogens.对病原体做出反应。 It's similar to becoming used to an annoying sound over time.这类似于随着时间的流逝习惯于令人讨厌的声音。

As you age, the reduced “attention span” of your innate and adaptive immune responses make it harder for the body to respond to viral infection, giving the virus the upper hand.随着年龄的增长,先天性和适应性免疫反应的“注意力跨度”降低,使人体对病毒感染的反应更加困难,从而使病毒占了上风。 Viruses can take advantage of your immune system's slow start and quickly overwhelm you, resulting in serious disease and death.病毒可以利用免疫系统的缓慢启动并迅速使您不知所措,从而导致严重的疾病和死亡。

社会疏远至关重要

Everyone, no matter their age, needs to protect themselves from infection, not just to keep themselves healthy but also to help protect the most vulnerable.每个人,无论年龄大小,都需要保护自己免受感染,不仅要保持健康,还需要保护最脆弱的人群。 Given the difficulty older individuals have in controlling viral infection, the best option is for these individuals to avoid becoming infected by viruses in the first place.鉴于老年人在控制病毒感染方面存在困难,因此最好的选择是让这些人首先避免被病毒感染。

在这里洗手,避免碰到脸,自我隔离和 社会疏远 都变得很重要 特别是对于COVID-19.

(为什么老年人受到Covid 19的威胁更大)打喷嚏喷出的薄雾可以将病毒传播到空中,因此其他人可以将其吸入。 詹姆斯Gathany, CC BY

COVID-19是由呼吸道病毒引起的,它可以通过微小的含病毒飞沫传播。 Larger droplets fall to the ground quickly;较大的水滴会迅速掉落到地面; very small droplets dry up.非常小的水滴干dry。 Mid-range droplets are of most concern because they can最关注中程液滴,因为它们可以 漂浮在空中几英尺 before drying.干燥前。 These droplets can be inhaled into the lungs.这些液滴可以吸入肺中。

与他人保持至少6英尺的距离有助于显着减少您被别人伤害的机会 被这些气溶胶滴感染。 But there's still the但是仍然有 病毒污染表面的可能性 that infected people have touched or coughed on.被感染的人已经感动或咳嗽。 Therefore, the best way to protect vulnerable older and immunocompromised people is to stay away from them until there is no longer a risk.因此,保护​​易受伤害的老年人和免疫受损者的最佳方法是远离他们,直到不再有危险为止。 By stopping the spread of SARS-CoV-2 throughout the whole population, we help protect those who have a harder time fighting infection.通过阻止SARS-CoV-XNUMX在整个人群中的传播,我们可以帮助保护那些难以抵抗感染的人。

本文借鉴了以下内容 最初发表的文章 3月19,2020。谈话

关于作者

微生物学,免疫学和病理学副教授Brian Geiss, 科罗拉多州立大学

本文重新发表 谈话 根据知识共享许可。 阅读 原创文章.

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