You may be thinking of smallpox, which exists in one or two declared labs (and probably a few more black labs).

Polio is unfortunately still "in the wild" in certain areas (Afghanistan/Pakistan/India, Sub-Saharan Africa), and had a bit of a resurgence lately. The Gates Foundation is putting a lot of effort into finishing up polio eradication.

Relevant TED talk: http://www.ted.com/talks/bruce_aylward_how_we_ll_stop_polio....

One of the main issues is that the polio vaccine requires a cold chain (presently; I think they have a new shelf-stable one); the smallpox vaccine, at least one of them, does not.