However, hepatitis B can also be transmitted by other body fluids, and in particular by sexual contact. Hepatitis B infections typically start several months after exposure to the virus, and can produce mild symptoms in some people. In others it can cause life-threatening liver damage. The original hepatitis B vaccines were produced using blood from people who had hepatitis B in the past. Today's vaccines are made using recombinant DNA techniques and contains no human or animal blood products.
Thimerosal is a mercury-based chemical.
Although no one has shown that thimerosal in vaccines poses a danger of mercury poisoning in infants or children, there is a theoretical risk of such poisoning. Now that thimerosal-free hepatitis B vaccines are available, the original schedule for hepatitis B vaccination, starting at or shortly after birth, has been resumed. There are two situations in which hepatitis B vaccine should be given before age 6 months. These babies should also get their second and third doses of vaccine at ages 1 and 6 months. For more information on hepatitis, including information on current outbreaks, check the Hepatitis Branch Home Page at the Centers for Disease Control and Prevention .