Frozen vials with “smallpox” labels found at a Pennsylvania lab contain the virus used in the vaccine for the virus and not the virus that causes the disease, public health officials said Thursday.
The Centers for Disease Control and Prevention said in a statement that laboratory testing showed that the vials contained vaccinia, which is similar to the smallpox virus and was used to inoculate against the eradicated disease.
They did not contain the variola virus, which causes smallpox, the agency said.
No one was exposed to the contents of the vials, and the agency said it notified local and state health officials, as well as the World Health Organization, about the lab results.
A lab worker reportedly found the vials in a freezer at a Merck facility in Montgomery County, northwest of Philadelphia.
The deadly disease was eradicated in the 1970s, but vaccines are kept in case of an outbreak. Only two facilities in the world are supposed to have vials of the smallpox virus — the CDC’s headquarters in Atlanta and a lab in Russia.