84 employees at the Centers for Disease and Control Prevention (CDC) in Atlanta were notified of their accidental exposure to the potentially deadly anthrax virus last week. Employees exposed working in lower-level security labs that were sent the virus without appropriate incubation time in higher-level security labs.

“This was simply a breach of protocol,” said CDC spokesman Benjamin Haynes in an email on Friday. “The protocol calls for inactive anthrax to be slided and observed after 48 hours to see if spores develop. This particular sample was checked and sent to lower-level labs after 24 hours.”

Lower-level security labs are not equipped to handle the live virus. Employees at these labs were unaware of the potential for the live virus, and were hence exposed to it unprotected, without the necessary equipment. As of last Thursday, 54 of the 84 exposed employees were seen by the CDC’s Occupational Health Clinic. Of the 54, approximately half opted for vaccination against anthrax, and all but two were taking oral antibiotics.

“Based on most of the potential exposure scenarios, the risk of infection is very low,” the CDC’s statement said, adding that “Out of an abundance of caution, CDC is taking aggressive steps to protect the health of all involved, including providing protective courses of antibiotics for potentially exposed staff.”

Anthrax became the focus of CDC bioterror labs all over the country after a 2001 incident that identified it as the most probable bioweapon. 5 individuals were killed from anthrax spores sent through the U.S. postal service in 2001. Scientists at CDC’s Bioterror Rapid Response and Advanced Technology lab, where the breach occurred, were preparing the anthrax samples for two laboratories focused on developing faster and more reliable methods to detect such spores.

According to the CDC website, even a very small amount can infect a large number of people. All strains of Anthrax left untreated could potentially spread throughout the body to cause severe illnesses, and potentially death, making it a highly likely agent for bioterrorism.