The covered entity (CE), Cook County Health, reported that a subcontractor of its business associate (BA) permitted drivers who were not registered with the BA to provide medical transportation to the CE’s health plan members. The CE determined that the unregistered drivers had access to the protected health information (PHI) of 898 individuals. The PHI involved included names, phone numbers, home addresses, and mobility status. The CE notified HHS, affected individuals, the media, and posted substitute notice on its website.