一个疑问

treeing261

Until mow, only injectable vaccines against influenza have been available.  arents are reluctant to subject children to the pain of injections, but adults, who are at risk of serious complications from influenza, are commonly vaccinated.  A new influenza vaccine, administered painlessly in a nasal spray, is effective for children.  However, since children seldom develop serious complications from influenza, no significant public health benefit would result from widespread vaccination of children using the nasal spray.
Which of the following is an assumption on which the argument depends?

A.    Any person who has received the injectable vaccine can safely receive the nasal-spray vaccine as well.
B.    The new vaccine uses the same mechanism to ward off influenza as jnjectable vaccines do.
C.    The injectable vaccine is affordable for all adults.
D.    Adults do not contract influenza primarily from children who have influenza.
E.    The nasal spray vaccine is mot effective when administered to adults.

此题答案为D选项
疑问：虽然大人能从小孩被传染流感，但题干中不是说了大人基本都打过疫苗了么？那就不怕被小孩感染了啊。
而E选项，因为大人一定会选择打疫苗，本来无痛疫苗如果可以给大人使用的话，大人也可能选择无痛的，这样无痛疫苗就有用了，但是因为E选项对大人无用的假设，题干推论才能成立。

因此为什么不选E？谢谢指导~

sdcar2010

Influenza: The conclusion is that the vaccine for children serves no health benefit.  What if when children catch the virus, the virus can be passed on to their parents?  If this is the case, then preventing the children from catching the disease could help their parents warding off the same disease, which is a health benefit.  To guard against this counter argument, the author HAS to make the assumption of answer D.

LZ, when the stimulus says that "The nasal spray vaccine is mot effective when administered to adults", then the vaccine will NEVER be effective for adults.  Do not add 这样无痛疫苗就有用了 by yourself!