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自1955年开始使用Salk脊髓灰质炎(以下简称脊灰)灭活疫苗,特别是1961年大规模使用活疫苗以来,在一些免疫较好的国家和地区,脊灰的发病率已急剧下降。显示
Since 1955, Salk polio (hereinafter referred to as Polio) inactivated vaccine has been used, especially since the large-scale live vaccine was used in 1961. The incidence of polio in some well-immunized countries has dropped dramatically. display