Commentary: poliomyelitis and unnecessary injections.

vaccines to prevent poliomyelitis have been available for 48 years, paralytic disease continues to occur in some areas, as reported by Kohler et al. 1 elsewhere in this issue of the International Journal of Epidemiology. Let us hope that by the 50th anniversary of the development of the first successful polio-myelitis vaccine all transmission of wild-type polioviruses will have ceased. The World Health Organization (WHO)-sponsored polio eradication programme has encountered and overcome many problems as we approach the final months of this enormously successful effort which has helped to revitalize immunization programmes throughout the world. 2 Transmission of naturally occurring wild-type 2 polioviruses has been interrupted ; there have been no wild-type 2 isolates anywhere for more than 2 years in spite of intensive surveillance. 3 Elimination of wild types 1 and 3 viruses will take longer, in part because three doses of oral poliovirus vaccine (OPV) induces protection against type 3 polioviruses in only 75% of children in developing countries. 4 Therefore, it is not surprising that 89% of the children with paralysis in the report by Kohler et al. had received three doses of OPV. The administration of supplemental OPV doses in national immunization day campaigns overcomes the incomplete protection, reaches children who do not receive recommended vaccines in routine programmes, and is an effective method of control. Administering one or more doses of inactivated polio vaccine (IPV) significantly improves the protection from three doses of OPV. 5 New problems have emerged in recent years that will make the global eradication effort more difficult than initially anticipated , including identification of immunodeficient persistent carriers of OPV-derived viruses 6 and outbreaks of vaccine-derived paralytic polio in several countries that had been certified as polio-free. 7,8 Also, new challenges will impact on the post eradication polio vaccination strategies in all countries, including the theoretical risk of using polio viruses as a bioterrorism agent and the successful synthesis of a wild-type poliovirus. 9 The industrialized countries that currently use IPV and other countries that are changing from OPV to IPV will continue to use IPV for many years after wild-type viruses have been eradicated. The difficult question facing WHO and developing country leaders is: Can routine OPV immunization stop in developing countries after eradication is certified? 10 If not, will some countries continue to use OPV and accept the risk of one case of vaccine-associated paralytic poliomyelitis (VAPP) for every 760 …