Hepatitis B is a liver disease caused by the hepatitis B virus (HBV). HBV causes the liver to swell and prevents it from working well.
About 95% of adults who are exposed to HBV fully recover within 6 months (acute HBV) without medication. About 5% have HBV all their lives (chronic HBV) unless they are successfully treated with medications. Infants born to mothers infected with HBV are at high risk of developing chronic HBV. Chronic HBV can lead to cirrhosis (scarring) of the liver, liver cancer, and liver failure.