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Group Health Cooperative of South Central Wisconsin

Disclosed Apr 8, 2024533,809 affectedConfirmed

Official notice

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.

What is known

People affected533,809 (as reported to HHS)
DisclosedApr 8, 2024
AttackHacking
Data exposedNamesHealth
SectorInsurance · US
StatusConfirmed

Sources

Notices filed

History of this record
Added2026-09-25
First recordedby backfillSource

First seen 2026-09-25 (HHS archive), confirmed by HHS OCR. Record counts are as reported. Not legal advice.

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