The hepatitis B vaccine protects your child against a liver disease that's caused by the hepatitis B virus. The virus is generally spread through bodily fluids like blood and in serious cases can lead to lifelong infection, scarring of the liver (cirrhosis), cancer, liver failure, and even death.
Children are most likely to contract hepatitis B from infected adults, including from infected mothers during birth (which is why the vaccine is administered to babies soon after they're born, before they leave the hospital). Unlike hepatitis A, this virus is not spread through casual contact or contaminated food or water. Adults are commonly infected with hepatitis B from high-risk behaviors like sharing needles or having sex with an infected person or from high-risk jobs (like the healthcare field) or blood transfusions.
About 30 percent of all adults who become infected with hepatitis B have no symptoms, although others may experience fatigue, nausea, loss of appetite, abdominal pain, joint pain, or a yellowing of the skin and eyes called jaundice. Infants and children aren't as likely to experience these symptoms, but about 90 percent of those who contract hepatitis B as babies and 25 to 50 percent of children who become infected before age 6 will become infected for life, increasing their risk for serious complications later on as well as spreading the disease to others.
Since routine hepatitis B vaccination of children began in 1991, the number of cases of hepatitis B in children and teens has dropped by 95 percent -- and by 75 percent across all age groups.