Polio eradication: strengthening the weakest links.

Polio eradication, like all eradication efforts, is a gamble. If it fails, much of the money spent will have been wasted. If it succeeds, the world will reap a dividend. Success or failure and the magnitude of the dividend depend on a long chain of "weakest links." In this paper I identify these links and explain how the chain can be strengthened. A crucial vulnerability is the current plan to halt vaccination using the live-attenuated oral polio vaccine in the post-eradication era. This weakest link can be strengthened by efforts that lower the cost to poor countries of vaccinating with the inactivated poliovirus vaccine.