Madison, Wis.-based UW Health began notifying 4,318 patients of a data breach in their Epic MyChart patient portal.
Between April 20 and May 4, an investigation identified unauthorized access to patients' MyChart accounts by an unknown third party, who may have viewed patient data, a June 18 news release said. The third party accessed patient portal accounts during various dates from Dec. 27 to April 13.
For some patients, the unauthorized party visited MyChart's patient portal homepage, which displays clinical information. Pages containing appointments and admissions, health insurance and personal information may have also been visited.
"UW Health deeply regrets that this incident occurred and for any concern it may cause," the news release said. "We take this issue very seriously and are committed to taking steps to help ensure something like this does not happen again. We are continuing to enhance its security processes and protocols including by strengthening password security, such as forcing password resets, requiring two-step validation for access to MyChart, and deactivating accounts that have been inactive for 15 months."