Back in the dark ages, circa 1981, children all over the world were dying of bacterial meningitis. Hemophilus influenza type b(H

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问题     Back in the dark ages, circa 1981, children all over the world were dying of bacterial meningitis. Hemophilus influenza type b(Hib)- the primary culprit - struck one in 200 kids in the United States alone, and a quarter of those who survived the infection suffered brain damage or hearing loss. Today, thanks to a new generation of vaccines, Hib is a rarity. Infection rates have fallen by more than 90 percent in developed countries, and some have vanquished the microbe entirely. Smallpox and polio have followed the same arc, and for the same reason. Vaccines, says Dr. Margaret Liu of the California-based Aviron Corp., have had "the greatest impact on human health of any medical intervention."
    The revolution isn’ t over. Armed with new tools for manipulating genes and proteins, scientists are now concocting vaccines to fight everything from food poisoning to cervical cancer. At the same time, they’ re discovering radical new ways to produce compounds that generate immunity. If the new strategies work, future vaccines won’t be manufactured in costly laboratories or doled out through needles. We’ll cull them cheaply from genetically altered fruits, vegetables or farm animals - and we’ll consume them in pills, ointments and nose sprays. Dozens of new compounds are in the works. And together with existing vaccines, they could prevent 12 million deaths a year worldwide.
    Now California-based Aviron Corp. is using a live, weakened pathogen to create a flu vaccine that can be placed in a nasal spray. Unlike conventional flu shots, which rely on killed viruses to rouse the immune system, Aviron’ s FluMist employs a live virus that thrives in cool climate of the nose and throat but perishes in warmer regions of the body. The bug provokes a vigorous response in the mucosal tissues that flu viruses invade, but its heat aversion keeps it from invading other tissues. Studies published this spring confirm that FluMist is effective. If approved by the FDA, it could reach the market as early as this fall.
From the passage it can be inferred that______.

选项 A、in future we can get immunity by consuming fruit, vegetables and farm animals
B、vaccines will be cheaper and easier to use
C、new vaccines can be used to fight any diseases
D、new vaccines will save 12 million lives a year worldwide

答案B

解析
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