"The synchronised vaccination campaign, one of the largest of its kind ever implemented in Africa, is part of urgent measures to permanently stop polio on the continent," the WHO said.
The programme will see all children under the age of five in 13 countries immunised from Saturday "in a coordinated effort to raise childhood immunity to polio," it added.
The countries are Benin, Cameroon, Central African Republic, Chad, Ivory Coast, Democratic Republic of Congo, Guinea, Liberia, Mali, Mauritania, Niger, Nigeria and Sierra Leone.
This year, the WHO has recorded four cases of polio - two each in Pakistan and Afghanistan. Last year, there were 37 cases globally.
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The four-day campaign in Africa by 190,000 vaccinators is part of the response to the discovery of three cases of polio in the insurgency-wracked state of Borno in northeast Nigeria last year.
Before then, the west African country had not reported a case of polio in two years and was on track to be certified free of the virus this year.
Lake Chad forms the border between Nigeria, Niger, Chad and Cameroon, which have all been affected by Boko Haram's Islamist insurgency.
"It's funded by international donors, local governments and the government of Japan who spent $33 million specifically to support this campaign," he said.
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.
"At that time, every single country on the continent was endemic to polio, and every year, more than 75,000 children were paralysed for life by this terrible disease," said Moeti.
"Thanks to the dedication of governments, communities, parents and health workers, this disease is now beaten back to this final reservoir.