We need to interrupt endemic transmission of wild poliovirus in limited areas within just four countries and a few other areas that have been reinfected.
我们只需要在四个国家的有限地区以及重新被感染的其它少数地区阻断野生脊灰病毒的地方性传播。
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On the other hand, even if males have a strong immune system that clears infection, they will become reinfected rapidly, so the effective benefit of immunity is low.