Vials found earlier this week at a medical lab that officials worried contained smallpox are actually a part of the vaccine against the virus, according to the CDC. File Photo by Michael Dukes/U.S. Army | License Photo
There was no smallpox virus in frozen vials recently discovered at a vaccine research facility in Pennsylvania, the U.S. Centers for Disease Control and Prevention said Thursday.
Instead of the variola virus that causes smallpox, lab tests showed that the vials contained vaccinia, the virus used in smallpox vaccine, according to the agency.
On Nov. 15, federal officials were alerted that the vials were found by a laboratory worker while cleaning out a freezer in the facility. The vials were sent on Nov. 18 to the CDC.
Before smallpox was declared eradicated in 1980 by the World Health Organization, the easily transmitted virus infected up to 15 million people a year and killed about 30% of them, CNN reported. The last known outbreak in the United States was in 1947.
In 2014, employees of the National Institutes of Health found six vials of smallpox in an unused storage room as they packed up a lab at the NIH's Bethesda, Md., campus to move it. Two of the vials contained viable virus.
The CDC said at the time there was no evidence anyone had been exposed to the contents of any of the vials.
There's disagreement among governments about whether to keep samples of smallpox or to destroy all known copies. Routine vaccination for smallpox stopped in 1972, but military personnel and some researchers still get vaccinated, CNN reported.
The CDC recommends that people who need long-term protection get smallpox boosters every 3-5 years, although at least one study found the vaccine might protect recipients for life.
Visit the U.S. Centers for Disease Control and Prevention for more on smallpox.
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