- State
- WI
- Covered entity type
- Health Plan
- Individuals affected
- 533,809
- Business associate present
- No
- Type of breach
- Hacking/IT Incident
- Location of breached information
- Network Server
- First seen by InfoSec Signals
- 9/23/2026
- Last seen in OCR export
- 9/23/2026
OCR description
The covered entity (CE), Group Health Cooperative of South Central Wisconsin, reported that it was the subject of a ransomware attack that affected the protected health information (PHI) of 533,809 individuals. The PHI involved included names, Social Security numbers, addresses, dates of birth and medial record numbers. The CE notified HHS, the affected individuals, the media, and provided substitute notice. In response to the breach, the CE provided complimentary credit monitoring services to the affected individuals and implemented additional administrative, technical, and security safeguards. Staff were retrained on the requirement to protect and secure PHI.
Change history
- 9/23/2026Added to OCR's archive list
Source: U.S. Department of Health and Human Services, Office for Civil Rights, Breach Portal. Records are reproduced as published; entity names and figures are OCR's.