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The Centers for Disease Control and Prevention (CDC) has completed an internal investigation of an incident that occurred in December within the agency’s Ebola virus laboratory, which resulted in no illness and was unlikely to have involved an exposure to live Ebola virus. The CDC’s investigation found that this laboratory incident occurred for two main reasons related to inadequate safeguards: lack of a written study plan that had been approved by a supervisor; and a study plan workflow that was not designed to sufficiently minimize the possibility that human error could result in potential exposure. CDC had already taken many steps to improve safety and will take additional steps as a result of this review.
In December, the CDC reported that a small amount of material from an experiment that was part of an Ebola virus study was securely transported from a selectagentapproved BSL4 lab to a selectagentapproved BSL2 lab and may have contained live virus. The material mistakenly transferred during procedures for this study was on a sealed plate but should not have been moved from the BSL-4 laboratory into the BSL2 laboratory. The study involved scientists placing identical oral swab samples from guinea pigs into two sets of tubes-one set of tubes for live virus studies and one set of tubes for studies with inactivated material. The tubes were identical in brand and size and only differentiated by color caps and labels. Appropriate and approved inactivation procedures, consistent with recently implemented laboratory safety improvements, were used. Unfortunately, however, human error resulted in the swabs being placed into tubes in such a way that another technician mistakenly transported the wrong specimens to the BSL-2 lab.
The report also describes two previous recommendations that had not yet been fully implemented in this lab that could potentially have reduced the likelihood of this incident: installation of a camera system for secondary verification of critical safety control points; and proper use of a required Material Transfer Certificate (MTC) form for materials taken out of CDC’s high containment laboratories to lower biosafety level laboratories, including internal transfers.
The CDC’s investigation found that immediate steps were taken to minimize any risk to CDC lab staff and that this incident was reported to appropriate authorities in a timely manner. In addition, the involved BSL-4 lab has suspended transfers out of the lab until a full review of the incident is completed and appropriate improvements are initiated. The CDC is currently installing camera systems in the BSL-4 laboratory and providing clear instructions on the intended use of the MTC form prior to resuming full BSL-4 operations.
The laboratory technician who worked directly with the specimens in the BSL-2 laboratory completed 21 days of direct active monitoring and reported no illness consistent with Ebola. The agency performed additional laboratory studies on swabs taken the workdays before and after the incident which found it was unlikely that the specimens transferred to the BSL-2 laboratory contained live Ebola virus. Although the studies determined there was no safety risk to CDC staff or the public, CDC will ensure continuous improvements occur to protect the safety of CDC staff and the broader community.
Among steps CDC is taking or has taken to address this incident:
• Enhance standard operating procedures for materials intended for inactivation and removal from laboratories to ensure that All materials are in standard, appropriately labeled, easily distinguishable tubes.
Multiple, redundant visual safeguards are used.
• Ensure CDC scientists have a full understanding of previously recommended laboratory safety improvements, including required use of the MTC form, and that they implement them.
• Work with CDC scientists from high containment laboratories to establish a peer-review system of written research plans to foster critical thinking on how to optimize workflows in protocols and minimize error.
While the incident described in this report highlights the need for continued enhancements to laboratory safety practices across the agency, CDC has made progress in this area over the past several months. Examples include:
• Established and recruiting for a new position, the Associate Director for Laboratory Science and Safety, with responsibility for providing agency-wide leadership and accountability for laboratory science, safety, and quality.
• Worked with laboratory staff and laboratory leadership to identify other safety improvement measures, including expansion of biosafety training and improvements in research standards and protocols.
• Undertaken an inventory of all stored biologic materials.
• Formed an external laboratory safety working group, under the Advisory Committee to the Director, composed of experts in biosafety and related areas to review and provide input into corrective actions and safeguards across all CDC laboratories.
CDC leaders have expressed their disappointment and have repeatedly stressed the importance of minimizing any potential risk to staff. The CDC’s efforts to improve lab safety are essential-with the safety of employees as the highest priority. The expertise and world-class knowledge that CDC scientists bring to laboratory work is vital and, while lab work will always carry some risk, it is crucial to saving lives and preventing disease. The CDC is committed to ongoing efforts to identify and implement systems and procedures that will allow the agency to provide maximum protections for laboratory staff and the broader community while conducting its critical laboratory work.
See the CDC’s laboratory safety site for the full report.