Walt Orenstein is with the Emory Vaccine Center. He says stronger vaccines might be helpful.

Walt Orenstein是埃默里疫苗中心工作人员。他表示，更强力的疫苗或许有帮助。

Mr. Orenstein says that health workers need to clear the last few areas where the polio virus exists.

Orenstein表示，卫生工作者需要清理脊髓灰质炎病毒存活的最后几个地方。