Public Health Response to Toxigenic Respiratory Diphtheria Outbreaks at Correctional Facility, South Africa, 2023-2025.

Since 2023, there have been 3 outbreaks of toxigenic respiratory diphtheria at a correctional facility in Cape Town, South Africa. The first outbreak in October 2023 included 1 fatal case and 8 asymptomatic carriers testing positive for Corynebacterium diphtheriae. In December 2024, the second outbreak resulted in 1 case and 12 asymptomatic carriers. A third outbreak in February 2025, occurring 6 weeks after the second, resulted in 1 case and 14 asymptomatic carriers among inmates and staff. Contact tracing, antimicrobial prophylaxis, and vaccination campaigns were conducted with each outbreak. We outline public health responses to the 3 outbreaks and highlight key barriers and enablers for effective control in a highly mobile, densely populated correctional setting. Effective outbreak response in correctional facilities requires intersectoral collaboration and the development of adult vaccination guidelines for staff and inmates to prevent future vaccine-preventable disease outbreaks.