CDC Lab Technician putting vials in centrifuge

A CDC lab technician may have been exposed to Ebola following an error in an Atlanta facility, the Centers for Disease Control and Prevention said on Wednesday.

The error happened on Monday when two sets of vials were mixed up. One vial contained an active sample of the virus, the other contained an inactive sample. A high-security lab sent the wrong vial to a laboratory unequipped to handle the live Ebola virus.

The technician in the second laboratory was wearing gloves and a gown when receiving the sample, but not a face shield.

The mistake was realized on Tuesday. Dr. Stuart Nichol, chief of the CDC’s Viral Special Pathogens Branch, attributed the mix-up to human error.

The potential exposure is under internal investigation and has been reported to Secretary of Health and Human Services, Sylvia Burwell. The mishap was also reported to the program that has oversight over “select agents,” which includes Ebola and anthrax.

Officials report the samples were properly contained and never left the facility, leaving no risk for exposure to the public.

The CDC lab tech has no Ebola symptoms but will be monitored for signs of the deadly virus for 21 days. Other employees who entered the lab will be examined as well.

Another CDC mishap happened in June. At least 52 workers had to take precautionary antibiotics after samples of anthrax and flu were mishandled. Employees failed to properly inactive the anthrax when transferring samples, putting many at risk.

After the anthrax incident, the CDC promised to improve its safety procedures. Outside experts were supposed to advise the agency on how to do so.

Dr. Thomas R. Frieden, director of the CDC, admitted the errors in labs were part of a bigger problem surrounding unsafe practices. Agency officials realized improvements needed to be made over the summer.

However, this recognition didn’t prevent a CDC lab tech’s potential exposure to Ebola six months after the anthrax mishap.