Hepatitis A is a serious liver disease caused by the hepatitis A virus (HAV). HAV is transmitted mainly via the fecal-oral route by person-to-person contact or ingestion of contaminated food or water. Symptoms of illness generally begin about 28 days after infection. Hepatitis A virus can be spread to others starting about two weeks before symptoms begin until about one week after symptom onset.
About 70% of infected children younger than 6 years of age will not have any symptoms. Infection in older children and adults is usually symptomatic and includes fever, malaise, nausea, abdominal discomfort, dark urine, and jaundice. There is no specific treatment for hepatitis A and most people recover within two months after symptoms begin. However, 10% to 15% of people will have prolonged symptoms and a small number will develop fulminant hepatitis A.
There are two hepatitis A vaccines: Havrix and Vaqta. Both are inactivated whole-virus vaccines. They are available in both adult and pediatric formulations. The pediatric formulations are approved for persons 12 months through 18 years of age. The adult formulations are approved for persons 19 years and older.
Hepatitis A vaccine is also available as a combination vaccine called Twinrix. Twinrix contains both hepatitis A and hepatitis B vaccines. Twinrix is licensed only for use in persons 18 years of age and older.
Product: Havrix® (Hepatitis A)
Year licensed: 1995
Product Name: Vaqta® (Hepatitis A)
Manufacturer: Merck & Co
Year licensed: 1996
Product Name: Twinrix® (Hepatitis A and Hepatitis B)
Year licensed: 2001
Older children and adults who did not receive hepatitis A vaccine in childhood and who fall into one or more of the following groups:
' Twinrix is approved for use in persons 18 years of age and older
*When hepatitis A antigens are given in combination with other antigens in one vaccine, the other antigens in the vaccine may cause other side effects. For more information about these possible side effects, go to the Hepatitis B.