Adults should receive one or both of these vaccines when they are at higher than average risk of contracting Hepatitis A or B or of suffering if they develop either disease. For hepatitis A, the major risks are travel to developing countries or chronic liver disease. For hepatitis B, risk factors include chronic liver or kidney disease, HIV, or regular contact with body fluids, as with healthcare workers. It is also possible to spread hepatitis B when sharing needles used with IV drugs. Hepatitis B can also be contracted if you are living with or in close contact with someone who is a hepatitis B carrier. This is why residents of certain long-term facilities should receive the vaccine. Hepatitis B can also be spread sexually, so anyone with multiple sexual partners or with a sexually transmitted disease should receive the hepatitis B vaccination.
The hepatitis A and B vaccines can be given separately or in a combined single-needle vaccine called Twinrix. The schedule for the hepatitis A vaccine is one dose and a booster dose six months later. The most common schedule for the hepatitis B vaccine is a dose at 0, 1, and 6 months. If someone needs both vaccines, they can receive Twinrix at zero, one, and six months. The extra dose of Hepatitis A is not considered significant. and the disease it protects against.