Citing a recurring problem with safety, U.S. officials have suspended the shipment of potentially dangerous germs from government laboratories in Atlanta to other labs.
The Centers for Disease Control and Prevention also shut down two of its laboratories where the recent safety lapses took place.
One of the closed labs was involved an incident last month that could have accidentally exposed workers in three labs to anthrax. No one was reported ill.
In an incident earlier this year, the CDC said another of its labs accidentally contaminated a sample of conventional flu virus with a deadly bird flu germ. That sample was then sent to another government lab.
CDC Director Dr. Tom Frieden announced the actions Friday.