Outbreak countries are those that have stopped indigenous wild poliovirus but are experiencing re-infection either through the importation of wild or vaccine-derived poliovirus from another country, or the emergence and circulation of vaccine-derived poliovirus.
To stop these outbreaks, it is necessary to fully implement international outbreak response guidelines.
Endemic countries, which have never stopped the transmission of indigenous wild poliovirus, can also be affected by outbreaks of circulating vaccine-derived poliovirus.
All countries remain at risk of polio until the disease has been completely eradicated from the world. Until then, the best way for countries to minimise the risk and consequences of polio infection is to maintain strong population immunity levels through high vaccination coverage, and strong disease surveillance in order to rapidly detect and respond to polio.