The Feb. 21 ransomware attack on UnitedHealth Group subsidiary Change Healthcare has impacted 100 million individuals.
The number of impacted individuals was posted on the Office for Civil Rights Breach Portal, which is used for reporting breaches of unsecured protected health information under HIPAA.
Previously, UnitedHealth said that the data stolen by hackers likely covered a "substantial proportion of people in America."
The cyberattack crippled financial operations for hospitals, insurers, pharmacies and medical groups nationwide. In July, the organization began sending out breach notification letters to individuals affected by the attack.
UnitedHealth said that it believes the hacking group ALPHV, also known as BlackCat, was responsible for the incident.