FBI investigating vials labeled 'smallpox' found in lab near Philadelphia

A bottle of smallpox vaccine held by gloved fingers.
A bottle of smallpox vaccine is held by a doctor at CDC headquarters in Atlanta in 2003. (Tami Chappell/Reuters)

WASHINGTON — The FBI and the Centers for Disease Control and Prevention are investigating “questionable vials” labeled "smallpox" and found in a freezer last night at a Merck facility outside Philadelphia, according to an alert sent to Department of Homeland Security leadership on Tuesday night.

There were reportedly a total of 15 questionable vials, according to the unclassified "For Official Use Only" alert, a copy of which was obtained by Yahoo News. Five of the vials were labeled as “smallpox” and 10 were labeled as “vaccinia." The vials were secured immediately.

The discovery of the vials prompted a lockdown of the facility, which has since been lifted. The FBI and CDC launched investigations, which remain ongoing.

“There is no indication that anyone has been exposed to the small number of frozen vials. The frozen vials labeled ‘Smallpox’ were incidentally discovered by a laboratory worker while cleaning out a freezer in a facility that conducts vaccine research in Pennsylvania,” a CDC spokesperson told Yahoo News.

“CDC, its Administration partners, and law enforcement are investigating the matter, and the vials’ contents appear intact. The laboratory worker who discovered the vials was wearing gloves and a face mask. We will provide further details as they are available,” the spokesperson said.

Smallpox, a disease caused by the variola virus, is considered so deadly that only two labs in the world are authorized to store samples of the virus, including one in Russia and the other at the CDC in Atlanta.

Three people in hazmat suits prepare to enter a building.
A hazmat team prepares to enter a building. (Douglas Graham/Roll Call/Getty Images)

Scientists have debated for years whether to destroy any remaining samples, citing the danger of a mishap that could unleash a disease that has been eradicated since the 1970s. Those in favor of keeping samples have argued they are needed to develop new vaccines in response to a new outbreak.

The majority of Americans are not vaccinated against smallpox, and those who were vaccinated would likely now have waning immunity.

The CDC will arrive on site tomorrow to take custody of the vials and transport them to another facility for testing, the alert notes. No personnel were reportedly exposed to the material.

“There is no indication that anyone has been exposed to the small number of frozen vials. The frozen vials labeled “Smallpox” were incidentally discovered by a laboratory worker while cleaning out a freezer in a facility that conducts vaccine research in Pennsylvania," the CDC said in a statement to Yahoo News. "CDC, its Administration partners, and law enforcement are investigating the matter and the vials’ contents appear intact. The laboratory worker who discovered the vials was wearing gloves and a face mask. We will provide further details as they are available.”

Merck, DHS and FBI did not immediately respond to a request for comment.