Health insurance giant Anthem Inc. said 13.5 million Californians were affected by the company's massive data breach that was disclosed earlier this month.
The nation's second-largest health insurer said a cyberattack had exposed names, Social Security numbers, dates of birth and other sensitive details on up to 80 million Americans.
Anthem has continued to investigate the depth of the data breach, and Tuesday it reduced that overall figure slightly to 78.8 million people affected. It also released more detailed numbers by state.
The tally in California is 13.5 million current and former Anthem customers dating back to 2004 as well as other Blue Cross Blue Shield members who received care in the state.
Large employers, for instance, often have workers scattered across the country and treated under various Blue Cross Blue Shield health plans.
Federal healthcare officials and state insurance commissioners are investigating whether Anthem took sufficient security measures to safeguard its massive database.
Connecticut officials said Tuesday that 315,000 people nationwide have signed up for the company's credit-monitoring services. Anthem declined to comment on exact figures.
In California, Anthem is the state's largest for-profit health insurer and leads the state insurance exchange in Obamacare enrollment.