Hepatitis B is caused by hepatitis B virus. Hepatitis B can be either without symptoms or acute or chronic symptomatic infection. The incubation period is long - up to six months (or even longer). Acute illness ranges from a mild to a very severe disease. Hepatitis B in children usually goes with no symptoms, with a higher tendency to become chronic. Conversely, the death rate of acute infection can reach 2% in the elderly. NEW

Those who become chronically infected by hepatitis B virus (from >30% among children to <5% among adults) are at a higher risk of serious consequences: liver cirrhosis (25%) and cancer (5%). Moreover, they act as a reservoir for continuing disease transmission. In recent years, increasing numbers of drugs are becoming available for treatment of chronic infection.

Hepatitis B is transmitted via contact (broken skin or mucosal contact) with blood or other body fluids (serum, semen, saliva) from infected patients. Chronic carriers usually remain infectious throughout their life. The incubation period ranges from one to seven months.

For infants and children, the main source of infection is mother-to-child transmission and transmission from infected members within the household. Adolescents and adults normally become infected through unprotected sexual activity or as a consequence of injecting drug users sharing contaminated needles. Transmission via blood transfusion or through the use of plasma-derived products is now rare in the EU.

Hepatitis B occurs worldwide with a very high burden of disease (an estimated 280 million carriers worldwide). HBV vaccination is currently the most effective way to prevent HBV infection.

Read more about hepatitis B in the factsheet for general public.