Several vials of the smallpox virus were found at a facility owned and operated by the US Food and Drug Administration (FDA) during a recent move of its Center for Biologics Evaluation and Research (CBER), government officials announced today.

The smallpox-causing variola virus, which is particularly hardy and extremely virulent, had been thought to exist only in two locations worldwide prior to the announcement by government officials—one group in Russia, and the other in the US.

Thanks to a worldwide vaccination effort, the virus has otherwise been eradicated.

But as the Centers for Disease Control and Prevention (CDC) announced today, last month FDA discovered that its Bethesda, MD campus was unwittingly host to a third group of smallpox samples—samples it was reportedly unaware even existed.

In preparation for a consolidation of FDA offices to the agency's headquarters in Bethesda, MD, FDA officials had been going through storage rooms.

Inside a cardboard box in an "unused portion" of a storage room within the facility, which had only been handed over to FDA in 1972, FDA reportedly stumbled upon a batch of smallpox-containing vials from the late 1950s.

CDC's statement said the vials were immediately secured in an agent contaminant laboratory in Bethesda, and have since been relocated to the CDC's Atlanta, GA headquarters for further testing and eventual destruction.

Six of the collected vials tested positive for variola DNA, though CDC officials were still determining if the samples could be infectious.

CDC Statement