國家地理:為了結(jié)束這場流行病 我們必須相信科學(xué)(3)

Make no mistake: The challenge is huge and unprecedented. If a typical virus is a riddle wrapped in a mystery inside an enigma, the coronavirus known as SARS-CoV-2 is all that and more. It combines contagiousness and lethality in a ferocious mixture that Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, has called his "worst nightmare." For one thing, when it appeared, no one on Earth had immunity. Second, it's airborne and infects the upper respiratory tract, which means it's readily spewed back into the air where it can drift from person to person. Third, and arguably worst, the virus is most contagious before it causes symptoms, meaning that carriers feel well enough to be up and about precisely when they're most likely to infect us.

毫無疑問，這項挑戰(zhàn)既艱巨又史無前例。如果說一種典型的病毒是包裹在謎團(tuán)中的一個謎，那么這個被稱為SARS-CoV-2的冠狀病毒更是如此。它結(jié)合了傳染性和致死性，美國國家過敏癥與傳染病研究所所長安東尼·福奇稱這個兇猛的組合為“最糟的惡夢”。首先，它出現(xiàn)時，世界上沒有人具有免疫力。其次，它通過空氣傳播感染上呼吸道，這表示它很容易再被噴回到空氣中，在人與人之間漂移。第三，也可以說是最糟的，這個病毒在引發(fā)癥狀前的傳染力最強，意思是攜帶病毒者感覺身體健康時，恰好是他們最有可能感染我們的時候。

The tricks this virus uses to foil the body's counterattack are diabolically effective. Once it gets inside via the nose or mouth, the coronavirus eludes the first line of immune defense, slides easily into cells, churns out copies of itself by hijacking the cell's machinery, and makes sure those copies work by using a proofreading mechanism that many other viruses don't even have. Its effect is relentless: It can turn a person's lung cells into useless material that looks like ground glass; blow open blood vessels or destroy them with microscopic clots; and gunk up the workings of a kidney, heart, or liver, rendering them too stiff to repair. It can defang the cells that attack invading viruses and then provoke a secondary immune reaction that goes badly haywire, paradoxically causing its own catastrophe. And anyone who comes in close contact with a person already infected is likely -- though no one is sure how likely -- to get infected too.

這種病毒用來阻擋人體反擊的招數(shù)很有效。新冠病毒一旦經(jīng)由口鼻進(jìn)入體內(nèi)，就會躲過免疫系統(tǒng)的第一道防線，輕易地進(jìn)入細(xì)胞，進(jìn)行復(fù)制，并且利用其他許多病毒都沒有的校正機制來確保復(fù)制的病毒功能正常。它會將人的肺部細(xì)胞轉(zhuǎn)變成毛玻璃狀的無用物質(zhì)，讓血管爆開或以微小血塊破壞血管，以及造成腎臟、心臟或肝臟功能受損，使它們變得過于硬化而無法修復(fù)。它可以削弱攻擊入侵病毒的細(xì)胞，能引發(fā)嚴(yán)重失控的次級免疫反應(yīng)，矛盾地造成自身體內(nèi)的災(zāi)難。此外，任何與已感染者近距離接觸的人也很有可能遭受感染――盡管沒人確定可能性有多高。