The are also efforts to develop a safer live attenuated vaccine, using more modern genetic methods. Sabin developed the original attenuated vaccine in the 1950

The are also efforts to develop a safer live attenuated vaccine, using more modern genetic methods. Sabin developed the original attenuated vaccine in the 1950s-60s, which is basically the stone ages, as far as genetics goes. We now know that the attenuated vaccine reverts to a more dangerous form of polio after it's administered, but that the time it takes to revert is long enough that the vast majority of people develop a robust immune response and don't develop paralysis. The problem is that there is an evolutionary path that the virus can take to revert, and that that path is heavily favored once the virus is actually inside a human gut. However, using modern genetic engineering techniques, it is possible to introduce a set of mutations into the polio virus that make it much more difficult for the virus to revert to a dangerous form. Scientists engineering viruses in a lab could sound scary to laypeople, but it's vital work that might lead to the final eradication of polio.