Hepatitis A: vaccine and disease
Hepatitis A vaccine is now recommended for universal administration to all infants 12 to 23 months of age, with a second dose six months later. We will be giving doses at 18 months and 2 years of age.
Hepatitis A is a serious liver disease caused by the hepatitis A virus. Hepatitis A virus is found in the stool of people with hepatitis A. Spread is through close personal contact and sometimes by eating food or water containing hepatitis A virus.
Hepatitis A can cause a wide variety of symptoms ranging from mild "flu-like" illness to more serious problems, such as yellowing of the eyes, severe stomach pains, and diarrhea, sometimes needing hospitalization. Hepatitis A usually is a mild, self-limited disease but the high incidence of infection results in about 100 deaths per year due to fulminant hepatitis. Additionally, while 70% of childhood infections are asymptomatic, they are still contagious and thought to be a major means of transmission of the infection.
The vaccine was originally recommended for states with the highest occurrence of hepatitis A virus, but worked so well, it's now recommended in all states.
About Hepatitis A Vaccine
Vaccination is the best way to protect against hepatitis A. People who get hep A vaccine have protection for years against infection with hepatitis A virus. The vaccine is made from a killed virus and is given as a shot in the arm. Before hep A vaccine was available, only short term protection could be achieved through the use of immune globulin.
Two vaccines to prevent hepatitis A are licensed in the United States. Both vaccines are inactivated products. The vaccine is administered as a two-dose series with the second immunization scheduled six months to 12 months after the first. Within two weeks of receipt of the first dose of vaccine, 94% of individuals have protective levels of antibodies; these levels rise to 100% after the second dose.
Longitudinal studies suggest that the two-dose regimen will provide protection for at least 20 years. No booster dose currently is recommended. While it is suggested to complete the two-dose series with the same preparation of hepatitis A vaccine, either of the two licensed products (GlaxoSmithKline's Havrix and Merck's Vaqta) may be used to complete the series without any known increase in adverse events or decrease in immunogenicity.
The vaccine is extremely safe. More than 6 million doses have been administered in the United States and to date no serious adverse event has been associated with the vaccine. The only contraindication to immunization with the vaccine is hyper-sensitivity to a component of the vaccine.