(Reuters) -The cyberattack at UnitedHealth Group's tech unit last year impacted 192.7 million people, the U.S. health department's website showed on Thursday.

In January, the company had estimated the hack at Change Healthcare affected the personal information of 190 million people.

The cyberattack - the largest healthcare data breach in the United States to date - was disclosed in February last year. The unit was infiltrated by hackers who identified themselves as the "Blackcat" ransomware group, causing widespread disruptions in claims processing and impacting patients and providers across the country.

The number of impacted people was posted on a list of data breaches maintained by the U.S. Department of Health and Human Services' office for civil rights.

UnitedHealth did not immediately respond to a Reuters request for comment.

Information made vulnerable in the UnitedHealth attack is believed to include health insurance member IDs, patient diagnoses, treatment information and social security numbers, as well as billing codes used by providers.