2. 外语
  3. 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,

admin2015-11-16  56
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.
In the author’s view, the new vaccine production method seems to be ______.
选项 A、remarkable
B、criticized
C、efficient
D、accepted
答案D
解析 由题干关键词new vaccine production定位到第一段最后两句。本文虽然主要介绍鸡蛋培育法，但也多处提到新的疫苗培育方法，即细胞培育法。专家就新方法能否阻止短缺现象未达成共识。因此D)与文中finally get the support含义最接近。
转载请注明原文地址:https://www.kaotiyun.com/show/hiQ7777K
0

大学英语六级

相关试题推荐
随机试题
最新回复(0)