Philadelphia lab briefly locked down after worker finds ‘smallpox’ vials in freezer

Worker found questionable vials' while cleaning out freezer, but CDC says no one was exposed to the deadly disease

A lab worker at a Merck facility outside Philadelphia found 15 questionable vials" labeled smallpox" and vaccinia" while cleaning out a freezer earlier this week, raising harrowing security concerns.

The FBI and the Centers for Disease Control and Prevention are investigating the discovery, which involves a disease that is believed to have killed over 300 million people since the dawn of the 20th century.