[Polio vaccines, eradication and posterradication].

Vaccination against polio generates herd immunity (both with the attenuated (OPV) and inactivated (IPV) vaccines) and this will allow the eradication of the disease. The OPV vaccine produces 2-4 polio cases per cohort of one million children and therefore IPV is used in countries that can afford its cost (about 15 times more expensive than OPV). In 1988 the World Health Assembly established the polio eradication goal as "interruption of wild poliovirus transmission".