Hepatitis B is a viral disease that affects the liver and is caused by Hepatitis B virus (HBV). As of 2015, 257 million people were living with the disease and Hepatitis B was responsible for 887,000 deaths per year. The disease has two stages, acute and chronic. During the acute phase, most cases are asymptomatic but a small proportion exhibit symptoms such as fever, jaundice, and abdominal pain, and less frequently severe liver acute infection. During the chronic stage, many of those infected develop cirrhosis (an abnormal liver condition causing scarring of the liver) and liver cancer.

HBV is distributed worldwide. The World Health Organisation (WHO) reports that approximately 240 million people are carriers of chronic hepatitis B virus infection. The virus can be transmitted through exposure to infected blood or body fluids, or during medical or other procedures involving needles. However, in high endemic transmission settings, the disease is transmitted mainly at the time of birth (perinatal transmission) and during childhood (from child to child). In adults, less than 5% of acute infections will lead to chronic infections; among infected adults infected, 20-30% will develop cirrhosis and/or liver cancer.

Prevention of Hepatitis B through vaccination is highly efficacious (~95%) and has been recommended by WHO since 1982. The scheme for the infant vaccination strategy consists of one dose at birth (preferably within 24 hours), followed by two doses given at the same time as the first and third doses of the DTP vaccine (diphtheria, pertussis (whooping cough), and tetanus) during routine vaccination programmes. Apart from this infant vaccination strategy, other interventions aimed at reducing the disease burden include the prevention of mother-to-child transmission and antiviral treatment to adults (which suppress viral replication and substantially reduces the risk of progression). The support from Gavi, the Vaccine Alliance, for Hepatitis B includes infant vaccination strategy as part of routine campaigns.

Model name: PRoGReSs (Hepatitis B model)
Model name: Hepatitis B model (Imperial College)
Model name: Hepatitis B model (Independent)

WHO fact sheet on HBV
CDC page on HBV
Gavi page on HBV