Polio for years has been close to becoming eradicated, with the entire continent of Africa going two years without a reported case – until early August. Here's why eradication is hard but attainable.
A new polio outbreak in Nigeria has hampered the country's efforts to be declared polio free by 2017.
Eradicating the last 1% of polio cases in the world requires an endgame plan centred on immunisation and surveillance.
The positive impact of the polio eradication initiatives on the continent can be felt across the health sector in other health programmes.
Nigeria's strategy to eliminate polio was so effective that it was duplicated to deal with ebola. So why did the country take so long to get off the list of polio-endemic countries?
It's been one year since the last polio case was reported in Africa. If the continent keeps this up, it could be declared polio free by 2018.