Influenza

流感

The centenary of the 20th century’s worst catastrophe

20世紀最大災(zāi)難一百周年

陳繼龍 譯

（本文英文版權(quán)歸《經(jīng)濟學(xué)人》所有）

“Spanish flu” probably killed more people than both world wars combined

“西班牙流感”致死的人數(shù)可能比兩次世界大戰(zhàn)死亡人數(shù)總和還要多

ON JUNE 29th 1918 Martín Salazar, Spain’s inspector-general of health, stood up in front of the Royal Academy of Medicinein Madrid. He declared, not without embarrassment, that the disease which was ravaging his country was to be found nowhere else in Europe.

1918年6月29日荔烧，西班牙衛(wèi)生總監(jiān)馬丁·薩拉查站在馬德里皇家醫(yī)學(xué)院前，不無尷尬地宣稱，肆虐該國的這一疾病在歐洲其他地方?jīng)]有出現(xiàn)。

In fact, that was not true. The illness in question, influenza, had been sowing misery in France and Britain for weeks, and in America for longer, but Salazar did not know this because the governments of those countries, a group then at war with Germany and its allies, had made strenuous efforts to suppress such potentially morale-damaging news. Spain, by contrast, was neutral, and the press had freely reported on the epidemic since the first cases had appeared in the capital in May. Before the summer was out, the disease Spaniards knew as the “Naples Soldier”—after a tune from a popular operetta—had been dubbed the “Spanish illness” abroad, and that, somewhat unfairly, was the name which stuck.

其實，這種說法并不確切。流感這一疾病已經(jīng)讓法國和英國遭受了數(shù)周的苦痛柬祠，美國時間更長。但是负芋，薩拉查并不知情漫蛔，因為那些國家的政府當時正與德國及其盟友交戰(zhàn)，所以想方設(shè)法壓制此類可能挫傷士氣的新聞旧蛾。相比之下莽龟，西班牙屬中立國，自首都5月出現(xiàn)首發(fā)病例起锨天，新聞界一直可以自由報道這一流行病毯盈。在西班牙人印象中，該病名叫“那不勒斯士兵”病袄，取自某流行輕歌劇里的一首曲子搂赋。（譯注：第一波流感來襲時，引人注目的音樂劇《遺忘之歌》（The song of forgetting）正在馬德里進行首次公演益缠。人們便借用此劇的角色和劇情脑奠，將“那不勒斯士兵”作為此次流感的綽號。）但夏天還沒結(jié)束幅慌，它就被外國冠以“西班牙病”之名宋欺，這是有點不公平，但這個名字就這樣叫開了胰伍。

Spanish flu was probably the worst catastrophe of the 20th century. The current estimate is that it killed at least 50m people and perhaps as many as 100m. At minimum, therefore, it ended the lives of three times as many as died in the first world war (in the region of 17m). It was probably also more lethal than the second world war (60m), and may well have outstripped the effects of both wars put together. The death toll was so high partly because Spanish flu was truly pandemic (some 500m people, more than a quarter of those then alive, are believed to have been infected),and partly because of its high mortality rate (5-10%, compared with 0.1% for subsequent influenza epidemics).

西班牙流感可能是20世紀最嚴重的災(zāi)難齿诞。據(jù)最新估計，它至少導(dǎo)致5000萬人死亡骂租，或許多達1億祷杈。所以說，被它奪走的生命起碼是第一次世界大戰(zhàn)死亡人數(shù)（1700萬左右）的三倍渗饮，也許比第二次世界大戰(zhàn)（6000萬）更為致命但汞，并且很可能超過兩場戰(zhàn)爭的總致死人數(shù)。死亡人數(shù)如此之多抽米，一方面是因為西班牙流感流行范圍確實非常廣（約5億人特占，亦即當時總?cè)丝跀?shù)中超過1/4的人都被認為染上此病）云茸，再者是由于其具有高致死率（5-10%是目，而后來的流感僅為0.1%）。

Understanding what happened is therefore important.Two questions in particular need answering. One is: what made this outbreak of influenza so much more lethal than both previous and subsequent ones? The other is: given that knowledge, what defences need to be put in place to nip any similar outbreak in the bud?

因此标捺，弄清發(fā)生了什么很重要懊纳。有兩個問題尤其需要解答：其一揉抵，是什么讓這場流感的爆發(fā)有著如此空前絕后的致命性？其二嗤疯，有鑒于此冤今，需要采取哪些預(yù)防措施，將類似的爆發(fā)流行遏止在萌芽狀態(tài)茂缚？

Origin of a species

物種的起源

The first cases of the 1918 flu to be recorded officially as such were at Camp Funston, a military base in Kansas, onMarch 4th 1918. That morning, Albert Gitchell, a mess cook, reported sick. By lunchtime the camp infirmary was dealing with dozens of similar incidents. The highly contagious nature of the Camp Funston outbreak suggests, however, that Gitchell was not the real “patient zero”. An emerging flu strain tends not to infect people very well at first. Researchers hunting for the individual Gitchell caught it from have therefore scoured records for an earlier, more localised outbreak of respiratory disease that quickly petered out.

據(jù)官方記載戏罢，1918年大流感病例最早于1918年3月4日出現(xiàn)在堪薩斯州一個軍事基地——福斯頓軍營。當日早晨脚囊，食堂炊事員阿爾伯特·吉切爾報告說自己病了龟糕。到午飯前，軍營醫(yī)務(wù)室處置了數(shù)十例類似病情悔耘。不過讲岁，福斯頓軍營爆發(fā)的疾病所具有的高傳染性表明，吉切爾并不是真正的“零號病人”（首例病人）衬以。新出現(xiàn)的流感病毒往往不會從一開始輕易傳染給人缓艳。因此，研究人員不再尋找可能把病毒傳染給吉切爾的個體看峻，而是從記錄中搜索發(fā)生時間較早阶淘、地點更為明確并且很快煙消云散的呼吸道疾病爆發(fā)事件。

At the moment, there are three theories as to where the 1918 flu first manifested itself. John Oxford, a British virologist, has long argued that it was in a British army camp at étaples on the northern French coast, not far from the Western Front. Here, an outbreak of“purulent bronchitis”, characterised by a dusky blue hue to the face, was reported as early as 1916. Such blue faces were also characteristic of fatal cases of Spanish flu.

關(guān)于1918年大流感最早在哪里顯現(xiàn)备籽，目前有三種看法舶治。英國病毒學(xué)家約翰·奧克斯福特一直堅持認為分井，這個地方是位于法國北海岸étaples的一座英國軍營车猬，離西線戰(zhàn)場不遠。有報告顯示尺锚，這里早在1916年就曾爆發(fā)過“化膿性支氣管炎”珠闰，其特點是面色發(fā)青。這種發(fā)青的臉部同樣也是西班牙流感死亡病例的特征之一瘫辩。

In 2004 John Barry, an American journalist, put forward a rival theory. He claimed that a small but severe outbreak of flu-like disease in Haskell County, Kansas, in January 1918, could have seeded the later one at Camp Funston. The camp’s catchment area for recruits includedHaskell.

2004年伏嗜，美國新聞記者約翰·巴里提出了不同的看法。他斷言伐厌，1918年1月在堪薩斯州哈斯克爾縣爆發(fā)過一次范圍不大但很嚴重的流感樣疾病承绸，可能為后來發(fā)生在福斯頓軍營的疫情埋下了禍根。這座軍營新兵的招募區(qū)域就包括哈斯克爾縣挣轨。

In 2013 a third hypothesis joined these two—or rather was revived, since it was fleetingly popular in the years immediately following the pandemic. According to Mark Humphries, a historian atWilfred Laurier University in Waterloo, Ontario, the 1918 flu began in Shanxi province, China, where an epidemic of severe respiratory disease in December1917 had doctors squabbling over its identity. Some thought it was pneumonic plague, a respiratory variant of bubonic plague to which China was distressingly prone. Others suspected a form of influenza.

2013年军熏，除上述兩種看法之外，又出現(xiàn)了第三種假說卷扮，或者說得準確些荡澎，就是自從大流行過后緊接著的幾年里曾經(jīng)一度廣受關(guān)注以來均践，再一次成為熱點話題。安大略省滑鐵盧市威爾弗瑞德勞里埃大學(xué)的歷史學(xué)家馬克·漢弗萊斯認為摩幔，1918年大流感始于中國陜西释（或山西省，音同）或衡，在那兒焦影，1917年12月發(fā)生過一次嚴重呼吸道疾病的流行，關(guān)于具體病種封断，醫(yī)生們曾爭執(zhí)不休偷办。有的認為是肺鼠疫，屬于腺鼠疫的呼吸道變種澄港，中國比較悲催椒涯，容易發(fā)生此病回梧；也有的人認為是流感的一種形式废岂。

Since they could not agree, and since it was also difficult to explain how the flu might have travelled from that remote and poorly connected region to the rest of the world, the theory fell by the wayside. Dr Humphries gave it new life when he pointed out that China, though neutral in the war until 1917, nevertheless played a role earlier than this date by providing Allied forces with a body of workers—the Chinese LabourCorps—who were recruited from provinces, including Shanxi, and shipped via Canada to Europe.

由于既無法形成一致意見，又很難解釋流感為何會從那個偏僻閉塞的地區(qū)傳播到世界其他地方狱意，這一理論只能半途而廢了湖苞。漢弗萊斯博士找到了新的證據(jù)。他指出详囤，雖然中國直到1917年在戰(zhàn)爭中都是中立國财骨，但是早在此前就通過為盟軍提供一批勞工即中國勞工營，在戰(zhàn)爭中扮演了某種角色藏姐。這些勞工來自包括陜西在內(nèi)的多個省份隆箩，用船經(jīng)加拿大被運往歐洲。

Dr Humphries’s hypothesis is weakened by work published the year following his proposal, by Michael Worobey, an evolutionary anthropologist at the University of Arizona, Tucson. Dr Worobey suggests that the 1918 human flu virus was genetically related to a virus circulating in North American birds at the time. The truth, though, is unlikely to be known unless and until a comparison can be made between the genetic sequence of the 1918 virus (which was determined in 2005, by Jeffery Taubenberger and Ann Reid of the Armed Forces Institute of Pathology inWashington, DC) and the sequences of each of the putative ancestors, of which, at the moment, no known samples exist.

在漢弗萊斯提出自己的假說一年后羔杨，圖森市亞利桑那州立大學(xué)進化人類學(xué)家邁克爾·沃洛比發(fā)表了一份研究報告捌臊，漢弗萊斯的推論也因此有些站不住腳了。沃洛比提出兜材，1918年人流感病毒與當時在北美鳥類中播散的一種病毒存在基因關(guān)聯(lián)理澎。然而，無人可以知曉真相曙寡，除非將1918年病毒基因序列（已由華盛頓軍隊病理研究所的杰弗里·陶本伯格和安·里德于2005年測出）與每一個可能的祖先基因序列進行比對糠爬，而就目前來看，并不存在這些祖先的已知樣本举庶。

The Blue Death

藍色死神

Whatever its origin, once Spanish flu got going it spread rapidly. It traversed the world in three waves, of which the second—that of the northern-hemisphere autumn of 1918—was the most severe. For that reason, the autumn of 2018 is marked by many as the epidemic’s centenary.

不論起源如何执隧，西班牙流感一發(fā)生就迅速蔓延開來。它分為三個波次橫掃全世界，其中第二波最為嚴重殴玛，于1918年秋天在北半球爆發(fā)捅膘。基于這一原因滚粟，很多人認為寻仗，到2018年秋天，大流行正好滿一百年凡壤。

That second wave was preceded by a milder one in the spring of 1918 and succeeded by a final wave, intermediate in severity between the other two, in the early months of 1919. The disease lingered on, though, until at least March 1920, with cases being reported that month in Peru and Japan. Indeed, Dennis Shanks, an epidemiologist at the Australian Army Malaria Institute, in Queensland, recently reported that the epidemic continued on some Pacific islands for another year, with cases still being reported in New Caledonia as late as July 1921.

第二波之前是1918年春季情況較為輕微的那一波次署尤，之后是最后一波，其嚴重程度介于其他兩個波次之間亚侠，發(fā)生在1919年前幾個月曹体。至少直到1920年3月，該病才逐漸消弭硝烂，當月秘魯和日本仍有病例報告箕别。實際上，昆士蘭澳大利亞陸軍瘧疾研究所流行病學(xué)家丹尼斯·山克斯最近報告說滞谢，之后該病在一些太平洋島嶼又持續(xù)流行了一年串稀，最晚到1921年7月，新喀里多尼亞仍有病例報告狮杨。

In the mind of Paul Ewald, an evolutionary biologist at the University of Louisville, in Kentucky, the 1918 virus’s global reach and its particular virulence were shaped by a common factor. Both were a consequence of the trench warfare of the Western Front.

肯塔基州路易斯維爾大學(xué)的進化生物學(xué)家保羅·埃瓦爾德認為母截，1918年病毒之所以波及全球且具有特別強的毒力，有一個共同影響因素——它們都是西線戰(zhàn)場陣地戰(zhàn)（塹壕戰(zhàn)）引發(fā)的后果橄教。

Its virulence, in Dr Ewald’s view, was a result of the abnormal evolutionary environment that the trenches provided.Normally, natural selection causes a virus that is transmitted directly from host to host to moderate its virulence. The longer the host stays alive, the more new hosts that initial victim is likely to come into contact with. Less virulent strains are thus favoured, and so spread. Observation shows that such drops in virulence do, indeed, happen in most influenza epidemics.

在埃瓦爾德看來清寇，1918大流感病毒的強毒力是由戰(zhàn)壕中異常進化環(huán)境造成的。正常情況下护蝶，由于自然選擇华烟，當病毒直接在宿主之間傳播時，其毒力也在減弱滓走。宿主存活越久垦江，初期受感染的宿主接觸到的新宿主也就越多。毒力較弱的病毒株也從而得以留存搅方，進而播散出去。觀察報告顯示绽族，大多數(shù)流感疫情確實存在這種病毒毒力下降的現(xiàn)象姨涡。

Dr Ewald, however, suggests that the war forced the 1918 virus down a different evolutionary path. The large numbers of young men packed into trenches in eastern France for days or weeks on end were, first of all, living cheek by jowl, making contagion easy, and, second, quite likely to die of causes other than influenza before they could pass it on. In these circumstances the strategy favoured by selection would be to breed rapidly in a new host’s body, shedding lots of virus particles as this happens,even if that risks killing a host—for the host may soon be unavailable anyway.

可是，埃瓦爾德指出吧慢，戰(zhàn)爭讓1918年病毒的進化“誤入歧途”涛漂。大量年輕人涌入法國東部的戰(zhàn)壕，一呆就是數(shù)日或數(shù)周，如此一來匈仗，首先瓢剿，他們在一起親密接觸容易造成傳染，其二悠轩，他們在把流感傳染給他人之前非常有可能死于流感以外的原因间狂。在這些環(huán)境條件下，自然選擇所采取的策略可能是病毒在一個新宿主體內(nèi)迅速繁殖火架，產(chǎn)生大量病毒顆粒鉴象，即使這樣存在致使宿主死亡的風(fēng)險，因為這個宿主也許很快就用不上了（根本不管宿主的死活何鸡，因為宿主本來也自身難保）纺弊。

Historians confirm that the virus did indeed race through the trenches, killing as it went. Those soldiers who survived then took it home with them when they went on leave. This process was exacerbated by the demobilisation which followed the armistice of November 1918that ended the fighting, with American, Australian, Canadian and New Zealand troops returning home, and also soldiers from the European combatants’ colonies in Africa and Asia.

歷史學(xué)家證實，病毒確實在戰(zhàn)壕中“賽跑”骡男，所到之處斃命無數(shù)淆游。那些幸存的戰(zhàn)士后來在休假時，又把病毒帶回家隔盛。1918年11月稽犁，停戰(zhàn)協(xié)議簽訂，戰(zhàn)爭結(jié)束骚亿，隨著美國已亥、澳大利亞、加拿大来屠、新西蘭軍隊虑椎，以及來自歐洲參戰(zhàn)國在非洲和亞洲殖民地的士兵回國，大量軍人復(fù)員加速了這一進程俱笛。

Most of those who fell ill from Spanish flu experienced nothing more than the symptoms of ordinary flu—a sore throat, fever and a headache. The unlucky, however, began to have difficulty breathing. Their faces took on a mahogany hue and they bled from their noses and mouths.Mahogany deepened to blue, an effect doctors dubbed “heliotrope cyanosis”, and before long their entire bodies turned black.

除了普通流感的癥狀如咽喉痛捆姜、發(fā)熱和頭痛之外，剛患上西班牙流感的患者大多數(shù)都沒有其他不適迎膜。然而泥技，不幸的人開始出現(xiàn)呼吸困難，臉部呈紅褐色磕仅，口鼻出血珊豹。紅褐色漸漸加深發(fā)青（也就是醫(yī)生所稱的“淡紫色發(fā)紺”效應(yīng)），不久后渾身變成黑色榕订。

The actual cause of death in most cases was pneumonia brought on by opportunistic bacteria. This made diagnosis complicated—for in 1918 the concept of a “virus” was a newish one. Most of the world’s doctors therefore thought they were dealing with a bacterial infection.The 1918 influenza thus appears in historical records under a kaleidoscope of labels ranging from the common cold to pneumonic plague. That is one reason why estimating the death toll accurately is hard.

大多數(shù)病例死亡的確切原因是細菌乘虛而入引起的肺炎店茶。診斷因此變得棘手，因為在1918年劫恒，“病毒”這一概念還屬于新生事物贩幻，當時全世界大多數(shù)醫(yī)生都認為他們診治的是一種細菌感染轿腺，進而造成歷史上關(guān)于1918年大流感的記載，從普通感冒到肺鼠疫千變?nèi)f化丛楚，紛然雜陳族壳。之所以很難準確估計死亡人數(shù)，這也是原因之一趣些。

At the molecular level, the explanation for the virulence of the Spanish flu remains unknown. But there are clues. Shortly after Dr Taubenberger and Dr Reid had worked out its genetic sequence, a group led by Terrence Tumpey, a virologist at the Centres for Disease Control andPrevention in Atlanta, Georgia, reconstructed the virus by feeding its genes to cultured human kidney cells in a dish, and forcing them to churn out viral particles in the way that human lung cells do during the normal process of infection. This reconstructed virus is now being studied at high-security biocontainment facilities in America.

目前還沒有從分子水平解析西班牙流感病毒毒力的相關(guān)結(jié)論仿荆，不過線索已經(jīng)有了。陶本伯格和里德測出其基因序列后不久喧务，一個由佐治亞州亞特蘭大的疾病控制與預(yù)防中心病毒學(xué)家泰倫斯·塔姆佩帶領(lǐng)的研究小組重構(gòu)了這一病毒赖歌，方法是將其基因注入培養(yǎng)皿中的人腎細胞，迫使其像正常感染過程中人肺細胞那樣大量產(chǎn)生病毒顆粒功茴。這一重組病毒目前正在美國高安全性生物防護設(shè)施內(nèi)接受研究庐冯。

One promising line of inquiry is the 1918strain’s version of haemagglutinin, a surface protein that helps the virus break into a target cell. When this is swapped into a strain of virus normally almost harmless to mice, it makes that strain deadly.

有一種研究體系前景，那就是1918年病毒株的血凝素說坎穿。血凝素是病毒表面的一種蛋白展父，可以幫助病毒侵入靶細胞。當血凝素被替換進一種通常對小鼠幾乎無毒的病毒株中玲昧，它會令那個病毒株變得致命栖茉。

Such work is controversial. Some critics point to possible military applications. Those working in the area, such as Dr Tumpey, prefer to emphasise its potential help to the job of creating better flu vaccines.

此類研究引發(fā)了爭議。某些批評人士指出其可能應(yīng)用于軍事孵延。這一領(lǐng)域的研究人員吕漂，比如塔姆佩博士，則更愿意強調(diào)其有助于推動研發(fā)更好的流感疫苗尘应。

Never again?

再也不會發(fā)生惶凝？

The glittering prize of such work would be a universal vaccine—something that protects recipients against all possible versions of the virus. One approach to creating such a vaccine exploits the observation that, although the convoluted head of the haemagglutinin molecule(which is the target of most existing vaccines), is highly variable in its composition, the stem that anchors it to the rest of the virus is not. A vaccine aimed at the stem might thus be universally effective.

此類研究若想獲得熠熠生輝的成果，就要創(chuàng)出一種通用型疫苗犬钢，保護接種者免受各種可能類型病毒的侵擾苍鲜。觀察發(fā)現(xiàn)，雖然血凝素分子（大多數(shù)現(xiàn)有疫苗的靶點）的彎曲頭部組成千變?nèi)f化玷犹，但其借以吸附在病毒其他部位的莖部是不變的混滔。因此，針對莖部的疫苗可能是普遍有效的歹颓。如果我們注意到這一點并加以利用坯屿，造出通用疫苗的方法也就有了。

Vaccines which employ this principle are already in clinical trials. But even if they do work, they might not be as universal as their supporters hope. Sceptics point to a phenomenon called imprinting, that might cause a “universal” vaccine’s efficacy to vary between individuals who have had different histories of exposure to flu.

應(yīng)用這一原理的疫苗現(xiàn)已進入臨床試驗晴股。但是即使有效愿伴，它們也許還是不會讓其擁躉如愿以償，做不到普遍適用电湘。懷疑人士指出一種被稱為“印記”的現(xiàn)象，它可能會使“通用”疫苗的效用因個體流感接觸史的差異而有所不同。

Imprinting is the name given to the observation that an immune system mounts its most effective response to the first flu strain it ever encounters. A memory of this first response is retained by the system and subsequent responses are therefore likely to be poor matches for new and different strains, whether caught from someone else or introduced by inoculation as vaccines. To the extent that haemagglutinin’s molecular stems really are the same in different strains, the effects of imprinting should be diminished. But they may not be abolished entirely.

人們觀察發(fā)現(xiàn)免疫系統(tǒng)會對其遇到的第一個病毒株產(chǎn)生最有效的免疫應(yīng)答寂呛，將這一現(xiàn)象取名為“印記”怎诫。免疫系統(tǒng)會保留這一首次應(yīng)答記憶，后續(xù)應(yīng)答因此可能無法準確針對新的不同的病毒株贷痪，不管是其他人傳染的還是疫苗接種后引入的幻妓。不同病毒株的血凝素分子莖完全相同，基于此劫拢，“印記”作用的影響也會減弱肉津，但并不會徹底消除。

Imprinting probably shaped the 1918pandemic. One of its surprises was that people in their twenties and thirties were particularly vulnerable, while the elderly—normally a high-risk group for flu—were actually more likely to survive than they had been in flu seasons throughout the previous decade. The first flu virus that most of those who were young adults in 1918 were exposed to as children was the one that caused the pandemic of the 1890s. This belonged to viral subtype H3N8 (subtypes are named after particular versions of haemagglutinin and a second surface protein, neuraminidase, that they contain), and was thus a different beast from the H1N1strain with which they were confronted in 1918, so imprinting would have harmed their response.

印記作用或許對1918年流感大流行產(chǎn)生了重要影響舱沧。那次大流行很多情況出乎意料妹沙，其中之一就是二三十歲的人特別容易被感染致命，而一般情況下屬流感高危人群的老年人相比前幾十年流感季熟吏，實際上存活率更高距糖。1918年的青壯年大多數(shù)在兒時就已經(jīng)最先接觸過流感病毒，而那個病毒是引起19世紀90年代大流行的病毒牵寺，屬于H3N8亞型（亞型是指病毒中所包含的血凝素與另一種表面蛋白神經(jīng)氨酸酶的特定變體）悍引，而他們在1918年遭遇的是H1N1病毒株，對于后者（H1N1）而言帽氓，就成了不同的動物宿主趣斤，于是印記作用就可能損壞他們的免疫應(yīng)答。

By contrast, there is evidence that those who were elderly in 1918 had often been exposed when young to viruses circulating earlier in the 19th century which contained H1 or N1. In their cases, imprinting would have helped their resistance mechanisms.

相比之下黎休，有證據(jù)顯示浓领，1918年的老人年輕時候常常接觸早在19世紀初期就已經(jīng)傳播的病毒，其中就包含H1或N1奋渔。對他們而言镊逝，印記作用則會促進其免疫防御系統(tǒng)。

Understanding imprinting could assist efforts to predict who will come off worst in a future pandemic, and to build abetter universal vaccine. The imprinting story is unlikely to be simple,though. For example, there seems to be cross-reactivity between some subtypes of influenza, meaning that exposure to one offers protection against another.America’s National Institute of Allergy and Infectious Diseases is planning a large study of imprinting in infants, to explore these effects.

了解印記作用嫉鲸，有助于預(yù)測在未來的大流行中誰最倒霉撑蒜，并研發(fā)一種更好的通用疫苗。不過玄渗，關(guān)于印記絕非三言兩語可以說清座菠。例如，流感的某些亞型之間似乎有交叉反應(yīng)藤树，這意味著接觸一種亞型可以防御另一種亞型浴滴。美國國家過敏和傳染病研究所正計劃一項針對嬰兒印記現(xiàn)象的大型研究，以探討這些影響岁钓。

The better vaccines promised by this sort of research are one arm of an effective response to a new pandemic. The other is early detection. The world has, thankfully, moved on from the point where a high-ranking health official can stand up four months into a flu pandemic and be ignorant of the situation in countries beyond his own. But the ability of a virus to spread around the world has increased hugely.

這類研究有望發(fā)現(xiàn)更好的疫苗升略，將為有效應(yīng)對新的大流行助一臂之力微王。另一個辦法是早期檢測。令人欣慰的是品嚣，現(xiàn)今的世界不會再有哪個高級衛(wèi)生官員在大流行都已經(jīng)持續(xù)4個月了還站著不動炕倘，而且對本國以外的情況一無所知。但是病毒在世界各地傳播的能力卻大大增加了翰撑。

Troops demobilised after the first world war went home by railway and ship. Now, passenger airliners mean that a virus in one part of the planet could cross to that place’s antipodes in a day.Moreover, though humanity at large is not as crowded together as were the troops in the trenches, the world’s population has quadrupled since 1918. About half of it now lives in cities, with a proximity between neighbours unknown to the far more rural world of a century ago. Monitoring systems are much better than they were in 1918, so the chances are that a threatening influenza outbreak would be picked up quickly. But the conditions needed for a pandemic to happen do exist. As with liberty, so with health: the price of retaining it is eternal vigilance.

一戰(zhàn)結(jié)束后遣散的部隊乘火車和輪船返回家鄉(xiāng)≌中現(xiàn)如今，客運班機意味著一種病毒可以在一天之內(nèi)從地球的一端橫跨到另一端眶诈。再者說了涨醋，盡管一般情況下人類不會像戰(zhàn)壕里的軍隊那樣擠在一起，但是自1918年至今逝撬，世界人口已經(jīng)增長了4倍浴骂，其中接近半數(shù)居住在城市，鄰里之間相距很近球拦，而這種情況對于一個世紀前以農(nóng)村為主的世界而言是并不存在的靠闭。相比1918年，現(xiàn)在的監(jiān)測系統(tǒng)先進得多坎炼，因此任何有可能流感爆發(fā)的跡象都會很快被發(fā)現(xiàn)愧膀。不過，發(fā)生大范圍流行的客觀條件仍確實存在谣光。自由也好檩淋，健康也罷，要想擁有萄金，就要永遠警醒蟀悦。