Savannah: We are like, SO close to eradicating polio. The naturally-occuring virus currently exists only in a small area on the border of Pakistan and Afghanistan, and the World Health Organization has set a goal to eliminate it in the wild entirely by the end of 2023.

So, why are researchers developing the first new polio vaccines since the '60s? Well, the problem is that these days the original virus isn't the only one to worry about. Weakened live viruses used in the previous generation of oral vaccines occasionally mutated to a communicable form, leading to outbreaks in places where vaccination rates were low. And while this mutated poliovirus remains really rare, it's still a wild card we don't need.

So, researchers have recently developed three new oral polio vaccines using viral strains engineered not to revert to a dangerous form of the disease. Which means that vaccination efforts in countries where poliovirus is still circulating can be even more effective.

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