Hepatitis B is a liver disease caused by the hepatitis B virus. As many as 1.25 million people living in the United States have hepatitis B. Not all people who are infected with HBV look or feel sick; they can have the virus and not have symptoms or know they are sick. Hepatitis B can be either "acute" or "chronic."
- Acute hepatitis B virus infection is a short-term illness that occurs within the first 6 months after someone is exposed to the hepatitis B virus. Acute infection can-but does not always lead to chronic infection.
- Chronic hepatitis B virus infection is a long-term illness that occurs when the hepatitis B virus remains in a person's body.
Hepatitis B vaccination is the most effective measure to prevent HBV infection and its consequences, including cirrhosis of the liver, liver cancer, liver failure, and death.
For more information about hepatitis vaccination for children, adolescents or adults, visit our Immunization Division or the Hepatitis B Foundation. The CDC is conducting a multilingual Know Hepatitis B campaign to encourage testing among Asian Americans.
Frequently Asked Questions
How likely is it that acute hepatitis B will become chronic?
The likelihood depends upon the age at which someone becomes infected. The younger a person is when infected with hepatitis B virus, the greater his or her chance of developing chronic hepatitis B. Approximately 90% of infected infants will develop chronic infection. The risk goes down as a child gets older. Approximately 25%–50% of children infected between the ages of 1 and 5 years will develop chronic hepatitis. The risk drops to 6%–10% when a person is infected over 5 years of age. Worldwide, most people with chronic hepatitis B were infected at birth or during early childhood.
How common is chronic hepatitis B in the United States?
In the United States, an estimated 800,000 to 1.4 million persons have chronic hepatitis B virus infection.
How common is chronic hepatitis B outside the United States?
Globally, chronic hepatitis B affects approximately 350 million people and contributes to an estimated 620,000 deaths worldwide each year.
Page last updated: May 3, 2019