What is Hepatitis B?

Hepatitis B (HBV) is a viral infection that infects the liver and requires direct contact with infected blood or other body fluids to be transmitted.

Symptoms of hepatitis B usually appear after 90 days and last for a few weeks. Symptoms include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, discolored (clay) bowel movements, joint pain, and jaundice (yellowish skin or eyes).⁽¹⁾

About half of infected adults and children over the age of five have symptoms of the disease, while many children under the age of five do not.⁽²⁾

Most acute hepatitis B infections do not persist and become chronic, but if the infection lasts six months or longer and persists without being cleared, it can lead to chronic liver disease, liver cancer, and death.⁽³⁾

Hepatitis B infection is diagnosed through a blood test. People with an acute hepatitis B infection have a positive hepatitis B surface antigen (HBsAg). HBsAg can be detected in blood as early as one week after the onset of infection and can persist for up to nine weeks. People who clear the infection have a positive hepatitis B surface antibody (HBsAb) that can be detected in their blood. Blood tests can take six months or longer to indicate whether an acute infection has cleared up or has become chronic.⁽⁴⁾ People who recover from an acute hepatitis B infection and who clear the virus are immune for life.⁽⁵⁾