Your medical data is not as safe as you think. Discover how a massive ransomware attack exposed millions and the key steps to protect your privacy now.

A cyberattack on UnitedHealth Group Inc. that paralyzed the US health-care system last year, snarling billions of dollars in payments for doctors and hospitals, also exposed sensitive data from 190 million Americans.

The number of individuals confirmed to be affected by the data breach is almost double the company's previous estimate.

Large-scale attacks on health providers expose the data of millions of Americans each year. Consumers must remain vigilant, experts say.