The Centers for Disease Control and Prevention is investigating the opening of vials labeled “smallpox” in a laboratory in Pennsylvania, the health agency said Thursday.
“The frozen vials were accidentally discovered by a lab worker while cleaning a freezer at a facility that conducts vaccine research in Pennsylvania,” CDC spokesman Belsey Gonzalez said Thursday in an email.
She added that the CDC has been working with law enforcement officials to investigate the vials. The agency said the vials were intact.
“The lab staff member who found the vials was wearing gloves and a mask,” she said. “There is no indication that anyone was exposed to a small amount of frozen vials. We will provide additional information as they become available. “
The CDC did not say where the vials were found in Pennsylvania, or how many.
Mark O’Neill, a spokesman for the Pennsylvania Department of Health, said that “a small number of vials” had been found at Merck’s Montgomery County facility, near Philadelphia.
Merck did not immediately respond to a request for comment on Thursday. The FBI has sent inquiries to the CDC.
“The Pennsylvania Department of Health would like to emphasize that there were no threats to public health and safety,” O’Neill said. “According to the CDC, there is no indication that anyone has been exposed to a small number of frozen vials that have been labeled ‘smallpox.”
Citing a notice from the state health department, Kelly Cofransisco, spokeswoman for the Montgomery County Communications Department, said there were a total of “15 questionable vials,” of which five were labeled “smallpox” and 10 labeled “vaccine.”
Smallpox, an infectious disease caused by the variola virus, has caused devastating outbreaks for centuries, with about 3 in 10 cases fatal, according to the CDC.
Symptoms include very high fever and blisters, and a progressive skin rash.
According to the World Health Organization, the virus claimed the lives of 300 million people in the 20th century.
In the event of an outbreak, “smallpox vaccine is sufficient to vaccinate every person in the United States,” according to the CDC.
The agency said the last natural outbreak of smallpox in the United States occurred in 1949. According to the WHO, the last known natural case was in Somalia in 1977.
WHO said there are two official repositories for variola virus stocks: the Center for Disease Control in Atlanta and a research center in Russia. In the same year, six glass vials of smallpox virus were found in a warehouse in a government laboratory outside Washington. At the time, the CDC stated that there was no indication that laboratory staff or the general public were exposed to the contents.
The CDC said research on smallpox in the United States is focusing on developing vaccines, drugs, and diagnostic tests to protect people from smallpox if used for bioterrorism.
Dr. Robert Glatter, an emergency doctor at Lenox Hill Hospital in New York, said smallpox can be fatal, “even after freeze-drying.”
Because of its high infectivity, he said, “the virus itself must be kept cold.” At room temperature, he said, after many years “the virus is unlikely to retain the ability to infect humans.”
Glatter added that discussions are ongoing about whether governments should preserve samples of the virus or destroy all known copies of the virus.