(Ed Note: This story has been corrected to better reflect the nature of the breach and to state that there is no evidence the data has been misused.)

Anthem BlueCross BlueShield has been hit with a data breach affecting more than 18,000 Medicare members, it reported to the government on July 24.

The data breach came from Anthem’s Medicare insurance coordination services vendor LaunchPoint Ventures. An employee emailed to himself data including Social Security numbers and Health Plan ID numbers, along with about 50 last names and dates of birth. LaunchPoint is contacting these individuals.

“LaunchPoint does not have any information to suggest that the data on the file was misused,” Anthem said in a statement.

“Launchpoint has terminated the employee, hired a forensic expert to investigate and is working with law enforcement,” the insurer continued, adding that the employee is now incarcerated for matters unrelated to the Anthem incident.

In a 2015 security breach at Anthem, hackers stole as many as 37.5 million records containing personally identifiable information. A settlement was reached that called for Anthem to improve its data security safeguards and required a credit protection program for the children affected by the breach. Senators also demanded Anthem release notifications on data breaches more swiftly after 2015.

LaunchPoint is providing fraud and identity theft protection resources to affected customers.

In an analysis done by Comparitech.com in July, it was discovered that following a data breach, a stock falls on average 0.43% and recovers in a little over a month, and that share prices grow more slowly for three years after a breach. The study also found that “breach fatigue” may be lessening the impact of a breach on a company’s stock performance.

— Check out Anthem, Centene Seek Attention for Higher Earnings on ThinkAdvisor.