Gaps in scientific knowledge for the post eradication world

There are significant gaps in the understanding of polio and polio vaccines which have programmatic importance even after 50 years of vaccine use. This paper considers four: the effect of strains used in the manufacture of IPV on safety and efficacy, the reasons for the safety of the Sabin strains, the nature and detection of long-term excreters of poliovirus and the basis for the cessation of virus excretion.