A: a vaccine-derived poliovirus (VDPV) is a rare strain of poliovirus, genetically mutated from the strain contained in oral polio vaccine (OPV).

答：疫苗衍生脊髓灰质炎病毒(VDPV)是一种罕见的脊髓灰质炎病毒株，由口服脊髓灰质炎疫苗(opv)里的病毒株遗传变异而来。

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Pakistan is affected by nationwide transmission of WPV1, and is the location of the only wild poliovirus type 3 (WPV3) case in Asia in 2011 (a strain on the verge of elimination on the continent).

巴基斯坦全国受到1型野生脊灰病毒传播的影响，并且是2011年在亚洲出现唯一一例3型野生脊灰病毒(在亚洲已濒临消除的一个毒株)病例的地方。

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