CDC: Scientist kept mum about dangerous bird flu blunder

An investigation into a potentially dangerous blunder involving bird flu samples at a government lab found that a scientist kept silent about the accident and revealed it only after other employees noticed something fishy.

Officials on Friday released the results of an internal probe into the accident, which happened in January at the Centers for Disease Control and Prevention in Atlanta. The CDC report cited "a lack of sound professional judgment by those aware of the contamination."

CDC officials have called this the most worrisome in a series of lab safety problems at the government agency. A potentially deadly strain of H5N1 bird flu was accidentally mixed with a tamer strain, and the mix was sent to another CDC lab in Atlanta and to an outside lab in Athens, Georgia.

No one was sickened by bird flu. But unsuspecting scientists worked with the viral mix for months before it was discovered.

CDC director Dr. Tom Frieden told CBS News last month that the mistake was discovered in late May but he wasn't told about it until early July.

"I remember it vividly," he told CBS News chief medical correspondent Dr. Jon LaPook. "I was sitting at my desk in our Washington office, and I was stunned and appalled that this could have happened and that there could have been this type of delay in notification."

Revelations about the bird flu mix-up followed another highly-publicized safety lapse involving anthrax. In June, the CDC reported that workers at its bioterror lab in Atlanta did not follow safety protocols while preparing potentially deadly bacteria to be moved to lower-security labs. There were concerns that as many as 84 employees of the lab could have been accidentally exposed, but no one got sick.

The head of the CDC's Bioterror Rapid Response and Advanced Technology Laboratory, Michael Farrell, later resigned.