The bottom line here...is that Smallpox will eventually return to our civilization (through an accident or through a terrorist method). For scientists to sit there and think they eradicated it from the Earth...is a joke. Its still around. And we (maybe not in my generation)...will see a return.
And your source for the assertion that "it's still around" is ...? The notion that a life form has gone extinct is not an exotic one. Seen a dodo or a mastodon lately? So why not a virus?
But I've also learned from this thread that a superstrain of smallpox broke out in Iran in 1972. It is possible that an Iranian lab has nurtured a smallpox culture for the last 33 years undetected. It's possible -- and therefore it's prudent to be prepared -- but I don't consider it likely.