RESUMO
Type 2 vaccine virus is the predominant cause of Vaccine-derived poliovirus and Vaccine-associated paralytic poliomyelitis. Therefore, World Health Organization recommends global synchronized switching from trivalent to bivalent Oral polio vaccine. To prevent the risk of type 2 poliovirus re-emergence, atleast one dose of Inactivated polio vaccine is recommended at 14 weeks of age in routine immunization, before the switch. To protect immunocompromised children and those under 14 weeks of age, an additional dose must be given at 6 weeks of age. Mass campaigns of Injectable polio vaccine in states with poor Routine immunization coverage, before the trivalent to bivalent Oral polio vaccine switch, will reduce risk of Vaccine-derived poliovirus by covering all under-immunized pockets. The additional costs are justified as it is our ethical obligation to eliminate any iatrogenic risk.