Healthcare Remains a Prime Target: Lessons from the Largest Data Breaches

Why Healthcare?

Healthcare organizations hold some of the most valuable data in the world. Patient records contain personal, financial, insurance, and medical information that cannot simply be replaced after a compromise. At the same time, hospitals, health plans, and healthcare providers depend on uninterrupted access to systems to deliver care, making them attractive targets for cybercriminals.

According to FBI data, healthcare experienced more cyber incidents than any other sector in 2025, including 460 ransomware attacks and 182 reported data breaches.

The scale of recent incidents demonstrates that healthcare organizations are not only dealing with more sophisticated threats, but also larger attack surfaces driven by cloud adoption, third-party vendors, connected medical devices, and growing numbers of identities.

Top 7 Healthcare Breaches Till Date

1. Change Healthcare (2024) — 192.7 Million Individuals

The Change Healthcare ransomware attack became the largest healthcare breach on record, impacting nearly 193 million individuals. Beyond exposing sensitive data, the attack disrupted payment processing across the healthcare ecosystem, delaying reimbursements and affecting providers nationwide.

2. Anthem Inc. (2015) — 78.8 Million Individuals

One of the most significant healthcare breaches ever recorded, the Anthem attack exposed names, Social Security numbers, addresses, and employment information of nearly 79 million people.

The incident highlighted how valuable healthcare records are compared to traditional financial data.

3. Welltok (2023) — 14.8 Million Individuals

The Welltok breach originated through a third-party file transfer platform vulnerability. While the attack did not directly target healthcare providers, patient information was still exposed through a trusted vendor relationship.

4. Aflac (2025) — 13.9 Million Individuals

Aflac’s breach demonstrated how healthcare and insurance organizations continue to face growing risks from sophisticated cyberattacks targeting large repositories of customer information.

The attack exposed personal and policyholder data affecting millions of individuals.

5. Kaiser Foundation Health Plan (2024) — 13.4 Million Individuals

Unlike many large-scale ransomware incidents, this breach involved unauthorized access and disclosure of sensitive information, emphasizing that external attackers are not the only threat organizations face.

6. CommonSpirit Health (2022)

The ransomware attack against CommonSpirit Health disrupted operations across hundreds of care locations, forcing some facilities to revert to manual processes and delaying patient services.

The incident demonstrated how cybersecurity events can directly affect patient care.

7. Ascension Health (2024)

The Ascension cyberattack affected operations across more than 140 hospitals and numerous senior care facilities. Clinical workflows were disrupted, illustrating how ransomware can rapidly move from an IT problem to an operational and patient safety issue.

Conclusion

Recent healthcare breach statistics suggest some improvement in reporting trends, but the underlying risk remains significant. The largest breaches of the past decade reveal a consistent pattern: attackers exploit gaps in identity security, third-party access, privileged accounts, and visibility across hybrid environments.

For healthcare leaders, reducing risk requires more than deploying additional security tools. The breaches highlighted in this article reinforce a common lesson: cybersecurity resilience starts with understanding identities, access, and trust relationships across the organization.

TechDemocracy partners with healthcare organizations to improve visibility, governance, and control so security teams can reduce risk while supporting patient care and business continuity.