WRHN Data Breach Exposes Personal Health Information of 150,000 Patients The Waterloo Regional Health Network (WRHN) has disclosed a security incident that may have compromised the personal health information of up to 150,000 patients. In a letter dated March 27, 2026, WRHN notified affected individuals that the breach stemmed from a third-party system hosted by Ontario Health used to share patient care details with primary health providers. The incident, detected and contained on January 13, 2026, occurred outside WRHN’s internal network, which remained secure. WRHN confirmed that clinical records and patient care were unaffected, with the breach resolved within hours of identification. However, the network acknowledged that data from April 2025 to January 2026 including clinical information may have been exposed. While WRHN’s investigation concluded there was a "low likelihood" of unauthorized access or misuse, the organization is notifying potentially impacted patients as a precaution. No immediate action is required from affected individuals, though WRHN encouraged reporting any suspicious activity. The incident has also been reported to the Ontario Privacy Commissioner. Ontario Health, the third-party provider, did not respond to requests for comment by the deadline.