Vials found at a vaccine research facility in Pennsylvania that were marked “smallpox” contained virus used to make the vaccine and not the virus that causes the disease, the US Centers for Disease Control and Prevention reported Thursday.
The CDC confirmed Tuesday that a few vials marked smallpox had been found at the facility.
Testing has now shown they contained vaccinia, a virus that’s related to the variola virus that causes smallpox. Vaccinia virus is used to make smallpox vaccine and is the origin of the word “vaccine.”
“There is no evidence that the vials contain variola virus, the cause of smallpox. CDC is in close contact with state and local health officials, law enforcement, and the World Health Organization about these findings,” the CDC said in a statement.
“On November 15, 2021, the U.S. Government was notified of the report of a small number of intact, frozen vials labeled ‘smallpox’ discovered by a laboratory worker while cleaning out a freezer in a facility that conducts vaccine research in Pennsylvania,” the CDC added.
“The freezer facility was immediately secured and staff followed standard protocols for notifying CDC of such a potential discovery. The vials were sent securely to CDC for testing on November 18 to determine what they contained. No one was exposed to contents of the vials.”
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Smallpox, which once killed a third of its victims, was declared eradicated in 1980 after a concerted, global vaccination campaign. That means it no longer exists in the wild and only a few laboratory samples are kept. Routine immunization stopped in the US in the 1970s.