HHS OCR report ยท 2023
Cook County Health and Hospitals System data breach
OCR report facts
- Covered entity
- Cook County Health and Hospitals System
- Entity type
- Healthcare Provider
- State
- Illinois
- Individuals affected
- 1,248,546
- Submission date
- Sep 24, 2023
- Type of breach
- Hacking/IT Incident
- Location of breached information
- Network Server
- Business associate present
- Yes
- Status
- Archive (closed)
OCR description
Cook County Health and Hospitals System, the covered entity (CE), reported that its business associate (BA) experienced a ransomware attack that compromised the protected health information (PHI) of 1,248,546 individuals. The PHI involved included names, addresses, dates of birth, Social Security numbers, diagnoses, and other treatment information. The CE notified HHS, affected individuals, and the media. In response to the breach, the CE terminated its business relationship with the BA.
Text as published on the HHS OCR breach portal.
Other reports by Cook County Health and Hospitals System
| Covered entity | State | Entity type | Individuals | Submitted | Type of breach | Status |
|---|---|---|---|---|---|---|
| Cook County Health and Hospitals System | IL | Healthcare Provider | 767 | Sep 15, 2014 | Hacking/IT Incident | Archive (closed) |
Frequently asked questions
How many people were affected by the Cook County Health and Hospitals System data breach?
The report to HHS OCR lists 1,248,546 individuals affected.
When was it reported to HHS?
It was submitted to HHS OCR on Sep 24, 2023.
What type of breach was it?
The OCR portal lists the type of breach as Hacking/IT Incident, with the breached information located in: Network Server.
Is the investigation still open?
No. The report is in the OCR portal archive, which holds reports where OCR has closed its review.
Is a breach notice letter from Cook County Health and Hospitals System legitimate?
This site cannot verify letters. Check the sender against the organisation's official website and the HHS OCR breach portal, and avoid calling numbers or clicking links only listed in an unexpected message. See our guide on what to do after a data breach notice.
Source: HHS OCR Breach Portal, OCR export October 2026. Network USA is not affiliated with HHS or Cook County Health and Hospitals System.