Two children living in areas of Nigeria controlled by terrorist group Boko Haram have been paralysed by polio, the World Health Organisation has said.
The infections represent a big setback for the WHO, which had previously thought it had managed to completely eradicate the virus from the country. The organisation was hoping to declare the country polio-free next summer.
Both children are from Borno, where half a million children have not been vaccinated against polio due to the presence of Boko Haram, the Verge reported.
Religious leaders in Nigeria have long been sceptical of vaccination drives, and the country has proven to be a tough nut to crack for immunization experts.
As recently as 2012, Nigeria accounted for more than half of all polio cases worldwide.