The new estimate nearly doubles the company’s previous report of 100 million affected individuals, already the largest healthcare data breach ever reported to federal regulators.

About 190 million Americans may have been affected by a cyberattack targeting UnitedHealth‘s subsidiary, Change Healthcare. The breach, which disrupted the company’s IT systems, resulted in the compromise of sensitive personal and medical information.

A cyberattack on UnitedHealth Group Inc. that paralyzed the US health-care system last year, snarling billions of dollars in payments for doctors and hospitals, also exposed sensitive data from 190 million Americans.

UnitedHealth Group says the impact from the cyberattack last year at its Change Healthcare subsidiary is much wider than previously understood, affecting

The attack, originally thought to have impacted about a 100 million Americans, is even larger than originally disclosed.

The cyberattack at UnitedHealth Group exposed personal information of 190 million people, leading to a $22 million ransom payment in bitcoin.