More than five million children were vaccinated against polio in Niger last month, the UN said on Tuesday, adding that the number was higher than the target.
The drive was broadened to include children in refugee camps whose parents had fled the Boko Haram insurgency in neighbouring Nigeria, the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said in a statement.
"In total 5,317,453 children under five years old were vaccinated against polio," it said, adding that the initial target was 4.5 million.
Nearly 42,000 children in refugee camps in the Lake Chad region were also included in the public health campaign.
Lake Chad forms the border between Nigeria, Niger, Chad and Cameroon, which have all experienced Boko Haram attacks.
Polio is a highly infectious viral disease, which mainly affects young children and can result in permanent paralysis. There is no cure and it can only be prevented through immunisation.
South Africa's former president Nelson Mandela launched a campaign to "Kick Polio Out of Africa" 20 years ago.
At that time every country on the continent had polio cases and more than 75,000 children were paralysed for life every year, according to UN officials.
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