Smallpox vials suspected to contain live virus

The Centers for Disease Control currently is testing decades-old vials of smallpox virus that were discovered last week in a storage refrigerator at the National Institutes Health in Maryland. Though six of the glass vials were found to contain smallpox DNA, health officials still don't know for sure if the samples are live and potentially hazardous.

Dr. Stephan Monroe, deputy director of the National Center for Emerging and Zoonotic Infectious Diseases at the CDC, told CBS News, "I will not be surprised if one or more of these samples contains live, growing smallpox virus."

In an exclusive interview with CBS News chief medical correspondent Dr. Jon LaPook, Monroe said the vials are now secured in a biosafety level 4, high containment laboratory at the CDC for testing. "It's possible but we don't know for sure if the smallpox virus in these samples will still be able to grow in the laboratory, and so that's the experiments that are currently ongoing," Monroe said.

The startling discovery of the smallpox vials by a researcher at the NIH required a multi-agency response from the NIH, CDC, FDA, World Health Organization, as well as the FBI and even the White House's National Security Council.

Monroe explained that the White House was notified because "smallpox is a potential bioterrorism agent, so anytime there is an issue that involves smallpox, the national security staff want to be informed."

The smallpox virus, also known as variola, was declared eradicated in 1980, thanks to worldwide vaccination efforts. Currently, samples of the virus only are permitted in two high-security labs in the world, at the CDC in Atlanta, Ga. and the State Research Centre of Virology & Biotechnology in Novosibirsk, Russia.

Monroe said the U.S. government has stockpiled a supply of the smallpox vaccine large enough to cover the entire country's population, just in case it should ever be needed.

He said he suspects at least some of the long-lost vials could contain live virus because the vaccine for smallpox is able to survive in conditions similar to where the samples were stored for more than five decades.

"What we do know is that things are very stable in a freeze-dried state, and for instance the vaccine that was historically used for the smallpox eradication campaign was freeze-dried and then typically stored in a freezer temperature and then was reconstituted right before use," he said. He added that if properly refrigerated some supplies of vaccines have been known to remain active for 20 years.

Only a select few people have access to CDC's biosafety level 4 lab, where the vials are currently being tested. The lab is protected with a high security system that includes surveillance cameras and alarm-protected doors. In order to check identity of people who enter, the facility uses an iris scanner which reads the unique pattern of an eye and matches it with records from an existing database.

Monroe said the CDC and World Health Organization have agreed to destroy the existing smallpox samples once they've been tested, though no timeline was given. "One thing that's reassuring is we know from previous experience how to control smallpox outbreaks and how to eliminate it from the world," he said.

As for the question of how these smallpox vials escaped notice for so many years, Monroe could only say it's "one of those flukes." He said it was a collection a researcher had put together, "but over time...the boxes were forgotten."

"Certainly one of the lessons learned from this episode is that laboratories around the world should have a firm idea of what they have in their collections and...should make an effort to do a complete inventory."