- State
- CA
- Covered entity type
- Health Plan
- Individuals affected
- 4,032
- Business associate present
- Yes
- 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), Health Plan of San Mateo, reported that a subcontractor of its business associate (BA) experienced a ransomware incident that affected the protected health information (PHI) of 4,032 individuals. The PHI involved included names, dates of birth, health insurance information, diagnoses, and health assessment information. The CE notified HHS, affected individuals, the media, and posted substitute notice on its website. In response to the breach, the CE and BA implemented additional administrative, technical, and security safeguards and retrained its employees.
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.