The United States closed two tightly guarded biological laboratories where missteps allowed lethal viruses to escape, the New York Times reports.
The move came after a June safety breach initially spurred fears that dozens of workers could have been exposed to anthrax at the Atlanta headquarters of the Centers for Disease Control and Prevention. In a separate incident disclosed on Friday, personnel at the center's influenza laboratory mistakenly transferred out a lethal strain of avian flu, together with a less dangerous virus.
"The Bioterrorism Rapid Response and Technology Laboratory will not be conducting work with any select agent until a series of reviews and approvals are completed," the Center said in a statement on Friday. "[Bioterrorism] laboratory scientists do not have access to select agents, which have been placed in storage-only mode."
"The CDC influenza laboratory is now closed and will not reopen until adequate procedures are put in place," the agency said.
Administrators also suspended all transfers of live and neutralized biological agents out of the agency's Biosafety Level 3 and 4 facilities.
CDC Director Thomas Frieden suggested the findings could lead to more stringent controls over facilities engaged in potentially hazardous biological research, the Times reported.
"One of the things that we want to do is reduce the number of laboratories that work with dangerous agents to the absolute minimum necessary. [We also want to] reduce the number of people who have access to those laboratories to the absolute minimum necessary," Frieden said in a Friday press briefing.
He added that two smallpox vials recently discovered in U.S. government custody appeared to still contain live viruses after more than a half-century.
"Whoever created these vials didn't do so out of malice. In fact, they come with the date of February 10th of 1954. That's when they were created," Frieden said.