UnitedHealth expects to restore disrupted services for medical claims and payment platforms by mid-March, the company said late Thursday. United's Change Healthcare unit is a vital lynchpin in the complex U.S. system for making and clearing insurance claims. The disruptions also impacted electronic pharmacy refills. While its pharmacy operations returned online on Thursday, UnitedHealth said its payment platform will be operational on March 15 and its medical claims network will be restored on March 18. The cyberattack on Feb. 21 at Change Healthcare was perpetrated by hackers who identified themselves as the ""Blackcat"" ransomware group, impacting doctors and medical practices across the U.S. healthcare system. Many doctors depend on the system to verify insurance coverage, file claims, and get paid, sparking a campaign by hospitals and doctors for the U.S. government to provide financial relief as it did during the COVID-19 pandemic.