Federal researchers stumbled upon several forgotten vials of smallpox last week that they believe date back to the 1950s. The vials have been sitting in a Food and Drug Administration laboratory in Maryland, properly labeled but located in an unused storage room where they've apparently sat unnoticed for decades. That could have been a major problem: smallpox has been eradicated from the globe, and because of international agreements, samples of the virus are only supposed to reside in two specific locations — one in the US and one in Russia.

All smallpox material will be destroyed

The Centers for Disease Control and Prevention transferred the vials to a high-containment facility in Atlanta last night and revealed the discovery and move today. Overnight tests confirmed the presence of smallpox in the vials, though further tests are needed to determine whether the material will be able to grow in a culture. The CDC says it expects testing to take up to two weeks.

The smallpox samples will all be destroyed once testing is complete, per World Health Organization rules. The WHO has been invited to both observe the virus' destruction and to further investigate the incident. The FBI and the CDC toxin division are also collaborating to investigate how these samples were overlooked. The lab that the samples were located in was originally operated by the National Institutes of Health but was transferred to the FDA in 1972. The lab is still located on an NIH campus, however, and it was in the course of moving the lab over to the FDA's headquarters that the samples were discovered.