It's cheap and easily-administered OPVs that have wiped Polio off the face of the earth except for a few regions where rabid antivaxxers keep it going.
The point about "shedding" Polio Vaccine is that in an area with endemic polio and poor sanitation, there will be a lot of full-strength wild polio in the envronment, especially in water polluted with sewage. Adults in that area will usually have some immunity because if they didn't die from it when young, they may just be crippled for life to some extent, or they may have no symptoms or be carriers. These people who still have the infection will be excreting it and perpeptuating the cycle of infection, disability and death through the generations.
A child or baby given the OPV will achieve a degree of immunity. Interestingly, they will excrete some of the weakened live vaccine. The upside is that other children exposed to sewage containing this weakened live vaccine have a chance of being infected by it and developing a degree of immunity from the weakened strain even if their antivaxxer parents prevented them from being immunised. Of course, in the environment I am describing, these children will be the lucky ones if they are infected by the attenuated strain rather than the virulent wild disease.
Interestingly, in a small but unknown number of cases, the attenuated strain can mutate back to a virulent strain over a period, and can then cause the disease. This is one of the reasons why when polio immunisation is carried out in one of the four countries in the world where it remains, due to obstruction by the antivaxxers, great efforts are made to immunise all the children at the same time, to prevent subsequent infection by a mutation. The children of antivaxxers in such a village would be at particular risk.
I look forward to the day when Polio is wiped off the face of the earth by extending vaccination to those few isolated corners where antivaxxers have managed to keep it going.
In the same way that Smallpox has been eradicated from the wild thanks to the strenuous efforts of healthcare teams providing vaccinations to all corners of the earth. No doubt there are antivaxxers who were not in favour of the eradication of smallpox.