As late as 1980, Polio was crippling 300,000 children every year. It's now down to a few hundred, at a bargain price of order $10B (total, not per year). It's natural to wonder whether it makes sense to push to fully eradicate the disease (which will cost billions more) rather than simply controlling it (presumably at a substantially lower cost) for a few decades until the regions become wealthy enough that eradication is cheap (at least relative to the local economy). This is not at all an obvious question; for organizations that are somewhat economically rational like the Gates Foundation, billions spend on eradication is billions not spent on other developing world interventions that might save more lives.

Here's the economic case for eradication:

http://polioeradication.org/wp-content/uploads/2016/07/Econo...