Towards global poliomyelitis eradication: the successes and challenges for a developed country.

The Sabin oral polio vaccine (OPV) has been remarkably successful, with three major regions of the world declared polio free. Mutations of the live attenuated poliovirus during genomic replication have resulted in polioviruses with increased neurovirulence. Recently, mutated vaccine-derived polioviruses have circulated in countries with low OPV vaccination coverage causing outbreaks of poliomyelitis in the islands of Haiti, the Dominican Republic, the Philippines and Madagascar. Ultimately the total eradication of poliomyelitis requires the cessation of OPV use. The current questions of how best to continue polio immunisation and when OPV should be withdrawn are addressed. Prolonged excretion of poliovirus in stools following cessation of vaccination has the potential to infect unimmunized susceptible children. In Australia the change to the use of inactivated polio vaccine (IPV), while more costly, will avoid the very low risk of vaccine associated paralytic poliomyelitis (one case per 2.5 million doses) and maintain immunity against polio. In the future, new vaccines may provide the solution to the problem of OPV cessation.