Now, the polio vaccine that Salk produced was very effective, but it required a fairly large dose of the vaccine and it had to be injected into the arms of children.

索尔克生产的小儿麻痹症疫苗效果显著,但是,该疫苗的单支注射剂量非常大,而且必须通过小孩的手臂进行注射

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