 This was expected to prevent new strains of cVDPV2 from arising and allow eventual cessation of WPV2 vaccination.The resulting global use of the injectable vaccine caused shortages, and a protocol using vaccine at one fifth the normal dose (fractional-Dose Inactivated Polio Vaccine, or fIPV) was introduced.There were 22 reported WPV1 polio cases with onset of paralysis in 2017, down from 37 in 2016.