A lot of didn't get sick from it now, and we got sick from it before.
许多人不会再因为微生物得病了,而人们以前则会因此生病
So you need hundreds of millions of doses, at least, and you need a way to distribute that around the world, and you need a way to keep track of who got sick and who didn't after they got vaccinated.
至少需要上亿支的剂量,还得有办法将疫苗运送到世界各地,你还要一种方法进行跟踪,在接种疫苗之后谁得病了和谁没得病
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