We'll think about it in section, how you don't need to vaccinate everybody, but you just need to vaccinate a critical number in order to stop the disease from progressing through a community.
我们在讨论会上讲这个,为什么不需要给每个人都接种,但你只需要让接种人数达到一个临界值,就能阻止这个疾病在社会中传播
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