To reach the goal of eradication, the GPEI partnership works tirelessly to strengthen surveillance, improve immunisation activities and ensure a rapid and effective response to any polio virus emergence. This work is essential to stop transmission and eradicate both wild polio virus (WPV) and vaccine-derived polio virus (VDPV) from the world.
There are 3 strains of the WPV, type 1, type 2 and type 3. WPV2 and WPV3 have already been globally eradicated, while WPV1 continues to circulate just two countries: Afghanistan and Pakistan.
VDPVs also occur in three types, like WPV. However, the emergence of a VDPV of any type only occurs in populations where not enough children are vaccinated. The live weakened virus from the oral polio vaccine (OPV) can circulate in an under immunised population through unvaccinated children. In very rare occasions with prolonged circulation the virus can genetically change into a form that can cause paralysis, just like WPV.
If a population is fully immunized against polio it will be protected against the spread of both WPV and VDPV.
