With sub-Saharan Africa on the verge of the largest polio epidemic in recent history, a United Nations-backed campaign to eradicate the virus has hailed resumption of immunization in the Nigerian State of Kano, seen as vital for eliminating the disease that once paralyzed hundreds of thousands of children worldwide each year. Immunization campaigns were suspended in various northern states of Nigeria in August 2003 following concerns by public figures regarding the safety of oral polio vaccine (OPV), including rumours that it was contaminated by the HIV virus or that it could sterilize young girls.