[cdtwigg]

The oral polio vaccine is a live vaccine and occasionally reverts to an actually infectious strain. This isn’t a major concern in countries where people are widely vaccinated but would be an issue if we considered it eliminated and stopped vaccinating segments of the population. https://en.m.wikipedia.org/wiki/Polio_vaccine

[gus_massa]

After some years without cases and if the country has a high vaccination rate, then the recommendation is to switch to use only the injectable vaccine. More details in the section https://en.wikipedia.org/wiki/Polio_vaccine#Schedule