成人往往对风疹有免疫力。
传播疾病的害虫也不甘落后，其中约有100种对目前使用的各种杀虫剂有了免疫力。
Not to be left behind are the disease-spreading pests, about 100 species of which have become immune to a variety of insecticides now in use.
这组科学家研究表明，麻疹病毒只需要一少部分易感儿童就能导致麻疹暴发，因此让尽可能多的儿童对麻疹有免疫力是很重要的。
According to the researchers, the measles virus only needs a small number of susceptible children to cause outbreaks, so it is important that as many children as possible have immunity to the virus.
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