Polio vaccine switch

Every country that was using trivalent oral polio vaccine (OPV) (containing all three serotypes of poliovirus) has permanently withdrawn this vaccine and either replaced it with bivalent OPV – containing only types 1 and 3 – or moved to an immunization schedule with only the inactivated form of polio vaccine (IPV).

Wild poliovirus type 2 has not been circulating since 1999 and was declared eradicated in September 2015. Removal of this eradicated serotype from the vaccine will further reduce the rare risk that a type 2 vaccine-derived poliovirus will emerge. The type 2 component of trivalent OPV also interferes with the immune response to poliovirus types 1 and 3.

For more information about the Polio Eradication Plan on the who.int website