Patients and health care providers have been struggling with various issues following a recent cyberattack on Change Healthcare, which is owned by UnitedHealth Group.

Dr. David Podwall is president of Nassau County Medical Society. He described the hack as “an absolute nightmare for most of the physicians around Long Island.”

Podwall explained that Change Healthcare is a clearinghouse connecting hospitals, physicians, pharmacies and patients.

Podwall said one out of three patient records in the country goes through this clearinghouse. As a result of the cyberattack, some patients can’t get their medications and some health care workers aren’t getting paid, among other problems.

Ronald Laszlo had a kidney transplant and relies on anti-rejection medication. He said he’s been off his medicine for days and is worried and “very depressed.”

UnitedHealth Group released the following information:

We are working aggressively on the restoration of our systems and services. Assuming we continue at our current rate of progress, we expect our key system functionality to be restored and available on the following timelines:

• Pharmacy services: Electronic prescribing is now fully functional with claim submission and payment transmission also available as of today. We have taken action to make sure patients can access their medicines in the meantime, including Optum Rx pharmacies sending members their medications based on the date needed.

• Payments platform: Electronic payment functionality will be available for connection beginning March 15.

• Medical claims: We expect to begin testing and reestablish connectivity to our claims network and software on March 18, restoring service through that week.