Officials with the U.S. Centers for Disease Control and Prevention on Friday announced that a vial labeled as smallpox and used as a test on a “sample of unknown origin” was found at a Pennsylvania laboratory.
The virus has been identified as vials of smallpox dating from the 1930s. Laboratory staff in the CDC’s Emerging Infectious Diseases Laboratory in Atlanta reported finding the vials last week. After testing, smallpox was confirmed as the source.
The vials were removed from the laboratory for further study Friday by the CDC’s infection control team, according to the Centers for Disease Control and Prevention.
After the discovery, procedures were implemented to confirm and contain the situation. All laboratory workers with direct contact with the vials were monitored, as well as all laboratory employees who could have come into contact with the vials, including human hosts. No evidence of exposure was found during these searches.
The vials were disposed of, and, as with all “imported” samples of smallpox, the CDC is not able to confirm the origin of the vials, the CDC said.
“If the source of the smallpox that was stored in Pennsylvania turns out to be a source of infection, it would not come as a surprise,” Dr. William Schaffner, chair of preventive medicine at Vanderbilt University Medical Center, said in a news release from Vanderbilt University.
He was among those consulted by CDC officials in response to the incident.
“These are handling practices that we’ve already been able to implement and already learned to be unsafe. Hopefully, this situation is an indication of how we’re moving forward,” Schaffner said.
Dr. Kevin Frazer, deputy director of the CDC’s Emerging Infectious Diseases Laboratory, told CNN, “we were concerned at the time,” and were able to remove the vials without any exposure to “employees or people who had contact with the specimens.”
It is important to note, according to Frazer, that smallpox was eliminated from the United States in 1980, long before the small vials were sent to the CDC. Still, learning from past mistakes is essential, he added.
“I think it’s important to say that we don’t know who held these specimens at one time, we don’t know how long they’ve been around or what happened to them. So it may be that some of these conditions are actually not protective, that the sample in some small way became immune to cure if it would be used for smallpox,” Frazer said.
There has been no immediate release of the source of the sample to the CDC, but according to Frazer, investigators are “scrambling” to understand how it got from an unidentified foreign national to the lab in the 1930s.
“So far, we have no additional cases and no contact of lab workers or people who’ve handled the specimens,” said Frazer.
The vials, containing smallpox, have been provided to international partners for the purpose of further scientific investigation, according to the CDC.
After learning of the finding, medical experts from around the world expressed concern over the small risk posed by the stored samples.
“This is very concerning. The fact that this could have been stored for years in a Cabinet box in some lab in the United States, should be a cause for alarm,” said Joshua Kaiser, assistant professor of infectious diseases and microbiology at Johns Hopkins Bloomberg School of Public Health.
“I believe they [the CDC] have learned the lesson from the Ebola disaster, that we need to be really, really careful to prepare and save our countries for even more severe diseases, not for something minor like this,” Kaiser told CNN.
Smallpox was declared eradicated from the world by the World Health Organization in 1980. The bacterium responsible for smallpox is not easily transmitted, but an infected person can pass it to others through close contact.
According to the WHO, the live and dead parts of the virus are stored in sealed containers at the CDC and other major laboratories. The CDC establishes laboratory protection protocols in response to any potential outbreak and regularly tests material from large shipments of out-of-date samples.