AFP and poliomyelitis: High-risk areas were defined as areas with low polio immunization coverage in combination with one or more of the following characteristics: 1) proximity to geographic areas with active WPV transmission; 2) a history of previous outbreaks in the area; 3) the presence of nomadic, mobile, or socially marginalized subpopulations; 4) inadequately functioning AFP surveillance systems; 5) the presence of insecurity, civil unrest, or armed conflict; or 6) a limited capacity to respond to outbreaks.