Global burden of hepatitis B, transmission routes, liver disease and cancer risk, and the evidence behind universal infant vaccination recommendations.
Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease. The hepatitis B virus (HBV) is a partially double-stranded DNA virus belonging to the Hepadnaviridae family. It is estimated that approximately 296 million people worldwide are living with chronic hepatitis B infection, with around 1.5 million new infections occurring annually.
Chronic hepatitis B infection is a leading cause of liver cancer (hepatocellular carcinoma) and cirrhosis. The World Health Organization estimates that in 2019, hepatitis B resulted in approximately 820,000 deaths, primarily from liver cancer and cirrhosis.
HBV is transmitted through contact with infected blood or other bodily fluids. The virus is 50-100 times more infectious than HIV.
Transmission from infected mother to newborn at birth is the most common route in endemic regions. Without intervention, 90% of infected mothers transmit to their infants.
Sharing of needles, syringes, or tattoo/piercing equipment contaminated with infected blood. Also a risk for healthcare workers through needlestick injuries.
Transmission through unprotected sex with an infected partner. The risk is higher with multiple sexual partners and in the absence of barrier protection.
Reuse of syringes and needles in healthcare settings, particularly in low-resource settings. Estimated to cause 1.7 million HBV infections annually.
Spread through sharing of personal items like toothbrushes or razors that may be contaminated with infected blood. Less common than other routes.
Transmission through contaminated blood products or organ transplants. Now rare in countries with screening programs.
Among adults infected with HBV, approximately 5-10% develop chronic infection. However, among infants infected at birth, up to 90% develop chronic infection. The risk of chronic infection is highest when infection occurs at a young age.
Chronic hepatitis B can lead to serious long-term complications:
The hepatitis B vaccine (recombinant DNA) was first licensed in the United States in 1981. It contains hepatitis B surface antigen (HBsAg) produced in yeast cells through recombinant DNA technology.
The standard 3-dose vaccine series (0, 1, and 6 months) provides long-lasting immunity in the majority of recipients. Studies show that protection lasts at least 30 years in most individuals who respond to the initial series.
ACIP recommends hepatitis B vaccination for:
Administering the first dose of hepatitis B vaccine within 24 hours of birth is critical in preventing perinatal transmission. When combined with hepatitis B immune globulin (HBIG) in infants of HBsAg-positive mothers, transmission risk drops from 90% to less than 10%.
WHO aims to reduce new hepatitis infections by 90% by 2030. Achieving this target requires scaling up birth-dose vaccination, particularly in high-endemic regions of Africa and Southeast Asia.