Startups are notoriously bad at keeping our data safe. Cerebral — a telehealth startup that launched into popularity during the early days of the coronavirus pandemic — has shared more than 3.1 million U.S. users' private health information with advertisers and social media platforms including Google, Meta, and TikTok.

In a disclosure first reported by TechCrunch, Cerebral said it used tracking technologies made available by third parties like Google, Meta, and TikTok. It's not uncommon for websites to use these kinds of tracking technologies for advertising and it's not uncommon for those practices to end in data breaches and, yes, even HIPAA violations.

That's just what Cerebral did: After reviewing its use of these technologies and data-sharing practices, the company "determined that it had disclosed certain information that may be regulated as protected health information under HIPAA" to some of those third parties. Cerebral may have accidentally given Google, Meta, and TikTok the personal information of its users such as names, phone numbers, email addresses, birthdays, IP addresses, results of their mental health self-assessments, treatments, and other clinical information. 

"Upon learning of this issue, Cerebral promptly disabled, reconfigured, and/or removed the Tracking Technologies on Cerebral’s Platforms to prevent any such disclosures in the future and discontinued or disabled data sharing with any Subcontractors not able to meet all HIPAA requirements," Cerebral said in the disclosure. "In addition, we have enhanced our information security practices and technology vetting processes to further mitigate the risk of sharing such information in the future."

The company's notice to customers is not easy to find. You have to scroll all the way to the bottom of the websitewhere you'll find, in small font: "See herefor more information on the March 2023 HIPAA breach." The social media companies that now have access to this data do not have to delete it, even if the data from Cerebral's breach is supposed to be covered under the U.S. health privacy law HIPAA.

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Cerebral is just one of the nearly 50 telehealth startups that shared user data with advertising platforms last year, according to a joint investigation by STAT and The Markup.