KEY POINTS
  • Quest Diagnostics says a data breach may have exposed the information of 11.9 million patients.
  • American Medical Collection Agency, a billing collections service provider, informed Quest of the breach.
  • AMCA said personal, financial and medical information may have been accessed.
A Quest Diagnostics requisition form is displayed for a photograph at Perry Memorial Hospital in Princeton, Illinois, U.S..

About 11.9 million Quest Diagnostics patients may have had their financial, medical and other personal information exposed in a data breach, the company said Monday.

In a filing with the Securities and Exchange Commission, Quest said a billing collections vendor, American Medical Collection Agency, notified it last month of potential unauthorized activity on AMCA's web payment page. AMCA provides billing collections services to Optum360, which is a Quest contractor. An unauthorized user had access to the system between Aug. 1, 2018, and March 30, 2019, Quest said.