This is why polio cases in Nigeria are now hovering near zero. According to the Global Polio Eradication Initiative (3.12.2014):
...almost 90% of Local Government Areas (LGAs) in the 11 high-risk states achieved coverage of at least 80% during last week’s conducted IPDs. This compares to less than 65% of LGAs in these same states achieving the same level of coverage just 12 months ago.
If 80% coverage continues and expands geographically, endemic circulation of polio in Nigeria will likely end.