MCG Health Data Breach Impacts 8 Organizations, 793K Individuals | TechTarget. About 793,283 individuals and at least 8 organizations were impacted by a third-party data breach stemming from MCG Health. As previously reported, Seattle-based company MCG Health suffered a data breach in March resulting from unauthorized access. The Seattle-based software company provides patient care guidelines to providers and health plans using artificial intelligence and technology solutions. According to a recent entry to the HHS Office for Civil Rights (OCR) data breach portal, the incident impacted 793,283 individuals in total. Since MCG disclosed the breach on June 10, at least eight organizations have come forward and said that they were impacted by the breach. Third-party company: MCG Health.