首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Modern technology has put men on the moon and deciphered the human genome. But when it comes to brewing up flu to make vaccines,
Modern technology has put men on the moon and deciphered the human genome. But when it comes to brewing up flu to make vaccines,
admin
2015-11-16
41
问题
Modern technology has put men on the moon and deciphered the human genome. But when it comes to brewing up flu to make vaccines, science still turns to the incredible edible egg. Ever since the 1940s, vaccine makers have grown large batches of virus inside chicken eggs. New cell-based technologies are in the pipeline, however, and may finally get the support they need now that the United States is faced with a critical shortage of flu vaccine. Although experts disagree on whether new ways of producing vaccine(疫苗)could have prevented a shortage like the one happening today, there is no doubt that the existing system has serious flaws.
Each year, vaccine manufacturers place advance orders for millions of specially grown chicken eggs. Meanwhile, Public Health officials monitor circulating strains of flu, and each March they recommend three strains—two influenza A strains and one B strain—for manufacturers to include in vaccines. In the late spring and summer, automated machines inject virus into eggs and later suck out the influenza-rich goop. Virus from the eggs’ innards gets killed and processed to remove egg proteins and other contaminants before being packaged into vials for fall shipment.
Why has this egg method persisted for six decades? The main reason is that it’s reliable. But even though the eggs are reliable, they have serious drawbacks. One is the long lead time needed to order the eggs. That means it’s hard to make more vaccine in a hurry, in case of a shortage or unexpected outbreak. And eggs may simply be too cumbersome(大量的)to keep up with the hundreds of millions of doses required to handle the demand for flu vaccine.
What’s more, some flu strains don’t grow well in eggs. Last year, scientists were unable to include the Fujian strain in the vaccine formulation. It was a relatively new strain, and manufacturers simply couldn’t find a quick way to adapt it so that it grew well in eggs. "We knew the strain was out there," recalls Theodore Eickhoff of the University of Colorado Health Sciences Center, " but public-health officials were left without a vaccine—and, consequently, a more severe flu season. "
Worse, the viruses that pose the greatest threat might be hardest to grow in eggs. That’s because global pandemics like the one that killed over 50 million people between 1918 and 1920 are thought to occur when a bird influenza changes in a way that lets it cross the species barrier and infect humans. Since humans haven’t encountered the new virus before, they have little protective immunity. The deadly bird flu circulating in Asia in 1997 and 1998, for example, worried Public Health officials because it spread to some people who handled birds and killed them— although the bug never circulated among humans. But when scientists tried to make vaccine the old-fashioned way, the bird flu quickly killed the eggs.
Which of the following statements is TRUE according to the passage?
选项
A、Flu vaccines now mainly use egg-based technology.
B、A bird influenza has once been circulated among humans.
C、Safety can be greatly improved with cell-culture vaccines.
D、Modern vaccine production methods are to replace egg-based methods.
答案
A
解析
结合选项定位到文中相关细节处。第一段第二句作者提到,对依然使用鸡蛋生产流感疫苗感到难以置信,接着第四句中作者指出,尽管每年有大批人死亡,有意思的是我们的第一防线依然是鸡蛋培育方法,因此A)正确。
转载请注明原文地址:https://kaotiyun.com/show/2iQ7777K
0
大学英语六级
相关试题推荐
Economistsusuallystudymarkets.Now,twoAmericanshavewontheNobelPrizeineconomicsfornotstudyingmarkets.Theywills
Economistsusuallystudymarkets.Now,twoAmericanshavewontheNobelPrizeineconomicsfornotstudyingmarkets.Theywills
A、Europeisthetopwineproducingarea.B、NoAfricacountrygraspsthewineproducingtechnology.C、Indiamakesanameforits
A、Ancientpeopleextractedjuicefromgrapes.B、Peoplestoredgrapesincontainersforwine.C、Juicefromripegrapesunexpected
A、Dogscansavepeople’slives.B、Dogscandistinguishdifferentsmells.C、Dogscanlearnhuman’sintentiontointeract.D、Dogs
A、Out-goingpeoplelikeankleboots.B、Amiablepeopleenjoyuncomfortableshoes.C、Aggressivepeoplelovewired-lookingshoes.D
A、Bygettingallergyshotsextractedfromhoney.B、Bysupplementinghoney-madefood.C、Byhavinglocalhoneydaily.D、Bytaking
Itcouldbepossibletolearnnewskillswhileyousleep,accordingtoAmericanscientists.ResearchersatYaleUniversityinves
Itcouldbepossibletolearnnewskillswhileyousleep,accordingtoAmericanscientists.ResearchersatYaleUniversityinves
A)TheSupremeCourtunambiguouslyruledWednesdaythatprivacyrightsarenotsacrificedto21stcenturytechnology,sayinguna
随机试题
Itwasessentialthattheapplicationforms______backbeforethedeadline.
环境空气质量监测点位置的周边环境应符合相关环境监测技术规范的规定。监测点周围空间应开阔,采样口水平线与周围建筑物的高度夹角()。
在某市城市区域火灾风险评估指标体系中,火灾危险源评估单元分为客观因素和人为因素两类,下列属于客观因素的有()。
计算机中网络通信协议中“TCP”指的是()。
“生产成本”账户的期末借方余额表示( )。
黄河公司以其房屋作抵押,先后向甲银行借款100万元,乙银行借款300万元。丙银行借款500万元,并依次办理了抵押登记。后丙银行与甲银行商定交换各自抵押权的顺位,并办理了变更登记,但乙银行并不知情。因黄河公司无力偿还三家银行的到期债务,银行拍卖其房屋,仅得价
宋代产生了中国绘画中最好的山水画,画家从细小的一只鸟、一朵花开始,最后扩大成为对宇宙自然全面的观察研究。与宋代这一绘画风格密切相关的是()。
回归教育是一种教育理论,它认为人的一生应是学习和工作不断交替、相互结合的过程。接受义务教育或基础教育乃至高等教育后就业的成年人,应在需要时有机会返回学校去学习。下列教育类型属于回归教育的是()。
在微机中,微处理器的主要功能是()
FairwayKenwoodisaqualityPrivateHireCarServicecompany.Thecompanyhasalongandestablishedservicehistorywithover
最新回复
(
0
)