When man tries to perfect biology that has heretofore worked I always ask what could possibly go wrong when such a Herculean effort as this is attempted. I know, too, that there are some in third world countries especially in the Middle East who will not give their children the vaccine as they think it a western plot, With that being said I simply HOPE the scientists involved in this polio vaccine swap effort know what they are doing.
All vaccines, no matter for what they are administered, carry risk. It is, however, ever-so-small compared to not being vaccinated at all. In our era of vaccination hysteria and misinformation I worry that some parents who have no idea the devastation the polio virus monstrosity can cause (ask me as I know well) and, therefore, will not trust a new vaccine for polio or, indeed, most anything else. This vaccine swap of a new polio vaccine in place of the old one better work. The task of doing this is massive.
I spoke at length about viruses to my relative who is a doc. I asked him if he thought the polio virus will always be there. He said an unequivocal yes. In other words if some refuse vaccination the virus will be there ready to enter its modality of transportation -- the gut. If one thinks the virus can be eliminated entirely I am quizzical. As Jurassic Park taught "life finds a way." Whether it's the AIDS virus or polio -- despite the simplicity of the polio virus -- it could mutate and evolve again to try to survive to live another day. I would hate to be at the bottom of Everest after I had just climbed that mountain only to see I must climb it again.