Stray vials of the deadly smallpox virus from the 1950s have been discovered at a federal laboratory near Washington - the second time in a month a deadly pathogen has been found at a US government facility.
Workers discovered the six glass vials in a cardboard box on 1st July while clearing out an old lab on the National Institutes of Health campus in Bethesda, Maryland, the US Centers for Disease Control and Prevention (CDC) said.
They contained freeze-dried smallpox virus and were sealed with melted glass. The vials appeared intact and there is no evidence that lab workers or the general public are at risk, spokesman Tom Skinner said.
Skinner said the CDC is working with the FBI to determine how and when the samples were prepared, and also how they came to be stored and forgotten in the lab.