(Reuters) - UnitedHealth Group ( UNH ) said the electronic prescribing for its pharmacy services is now fully functional, with claims submission and payment transmission also available after cyber attack on its tech unit Change Healthcare impacted services.

UnitedHealth ( UNH ) said on Thursday that electronic payment functionality for its payments platform will be available for connection on March 15, adding that it expects to begin testing and reestablish connectivity to its medical claims network and software on March 18.

The cyberattack on Feb. 21 at Change Healthcare was perpetrated by hackers who identified themselves as the "Blackcat" ransomware group, having a knock-on effect on players across the U.S. healthcare system, as disruptions triggered by the attack have impacted electronic pharmacy refills and insurance transactions.

Change Healthcare is a vital lynchpin in the complex U.S. system for making and clearing insurance claims, connecting providers to not just UnitedHealth ( UNH ) but also to CVS Health's ( CVS ) Aetna, Elevance, Humana, and others.