Vials Found at Pa. Lab Did Not Contain Smallpox Virus, CDC Says

The CDC determined there was no evidence that the vials contained variola virus, the cause of smallpox

What to Know

  • On Monday, government officials were notified of the report of a small number of intact, frozen vials labeled “smallpox” that were discovered by a laboratory worker while cleaning out a freezer at the Merck Upper Gwynedd facility.
  • The CDC determined there was no evidence that the vials contained variola virus, the cause of smallpox.
  • Instead they said the vials contained the virus used in the smallpox vaccine.

Vials labeled “smallpox” that were found at a Montgomery County lab did not contain the virus known to cause smallpox but instead contained the virus used in the smallpox vaccine, the Centers for Disease Control and Prevention (CDC) announced Thursday. 

On Monday, government officials were notified of the report of a small number of intact, frozen vials labeled “smallpox” that were discovered by a laboratory worker while cleaning out a freezer at the Merck Upper Gwynedd facility in North Wales, Pennsylvania, about 30 miles northwest of Philadelphia. The facility conducts vaccine research in Pennsylvania. 

Officials say the freezer facility was immediately secured and staff followed standard protocols by notifying the CDC. The vials were then sent securely to the CDC for testing on Thursday. 

The CDC determined there was no evidence that the vials contained variola virus, the cause of smallpox. The CDC also said they are in close contact with state and local health officials, law enforcement and the World Health Organization about their findings and that no one was exposed to the contents of the vials.

Smallpox dates back as early as the 6th century, and for centuries spread uncontrolled throughout the world. About 3 in 10 people who contracted the disease died, according to the CDC. It was spread as a virus called variola. A vaccine was invented in 1796, but it wasn't for nearly another 200 years before the last known cases in the late 1970s.

"Following the eradication of smallpox, scientists and public health officials determined there was still a need to perform research using the variola virus. They agreed to reduce the number of laboratories holding stocks of variola virus to only four locations," the CDC says on its website.

"By 1984, England and South Africa had either destroyed their stocks or transferred them to other approved labs. There are now only two locations that officially store and handle variola virus under WHO supervision: the Centers for Disease Control and Prevention in Atlanta, Georgia, and the State Research Center of Virology and Biotechnology (VECTOR Institute) in Koltsovo, Russia."

Contact Us