This was a bit of a half-truth. Although there hasn't been an outbreak of smallpox since 1980 (*touches wood*), the World Health Organization arranged for two samples of the virus to be kept behind, in case we ever needed them. For additional security, the vials were then split between the U.S. and Russia, where they remain to this day -- in Atlanta, and Novosibirsk Oblast, respectively.
That was nearly forty years ago, and to put it lightly, everyone is starting to wonder when the WHO is going to hang up their letterman jacket, stop clinging to the past, and incinerate those samples before something bad happens. In 1999, see, the WHO formed an advisory committee to oversee the samples, approve/reject research proposals involving them and, ultimately, make the call on when to pull the plug, something that it has steadfastly refused to do.
The thing is, though, there isn't a clear-cut answer to this dilemma.
The argument made by the WHO (and a large contingent of scientists) is that keeping the samples enables scientists to research vaccines and other treatments that may help us if smallpox ever decides to make a reappearance, which is a fair point seeing as how, several years ago, researchers found previously-unknown vials of live smallpox sitting in someone's office -- and besides, we've been trying to get rid of ebola for the last umpteen years. No matter what we do, it keeps coming back.
To sum up, then, getting rid of the samples may leave us defenseless in the face of a future smallpox pandemic. That sounds pretty convincing, to be honest, it's hard to see how the doubters are going to come back from that one.
On the flip side, just as many scientists and authorities have argued that there's no research nowadays that can't be done on gene fragments that have been sequenced from the live virus, as well as other strains like monkeypox -- and that by keeping the samples around, we're only increasing the likelihood that the virus might accidentally (or intentionally) be released, which is a fair point seeing as last year, the facility holding one of these samples was hit by a gas explosion. The virus was never in danger of being released, but that's not exactly reassuring, is it?