Two hepatitis A vaccines are available in the US, hepatitis A vaccine (Havrix, Vaqta). Both contain inactive (killed) hepatitis A virus. For adults, two doses of the vaccine are recommended. After the first dose, protective antibodies develop in 70% of vaccine recipients in 2 weeks and more than 95% of recipients in 4 weeks. After two doses of the hepatitis A vaccine, immunity against hepatitis A infection is believed to last for many years.
Individuals at increased risk for acquiring hepatitis A and individuals with chronic liver disease (for example, cirrhosis or chronic hepatitis C) should be vaccinated. Although individuals with chronic liver disease are not at increased risk for acquiring hepatitis A, they can develop serious (sometimes fatal) liver failure if infected with hepatitis A and, thus, they should be vaccinated.
Individuals at increased risk of acquiring hepatitis A are:
- Travelers to countries where hepatitis A is common
- Men who have sex with men
- Illegal drug users (either injection or non-injection drug use)
- Researchers working with hepatitis A or primates that are susceptible to infection with hepatitis A
- Patients with clotting factor disorders who are receiving clotting factor concentrates that can transmit hepatitis A
Some local health authorities or private companies may require hepatitis A vaccination for food handlers.
Because protective antibodies take weeks to develop, travelers to countries where infection with hepatitis A is common should be vaccinated at least 4 weeks before departure. The Centers for Disease Control (CDC) recommends that immunoglobulin be given in addition to vaccination if departure is prior to 4 weeks. Immunoglobulin provides quicker protection than the vaccines, but the protection is short-lived.
For active vaccination, a harmless hepatitis B antigen is given to stimulate the body's immune system to produce protective antibodies against the surface antigen of hepatitis B. Vaccines that are currently available in the U.S. are made (synthesized) using recombinant DNA technology (joining DNA segments). These recombinant hepatitis B vaccines, hepatitis B vaccine (Energix-B and Recombivax-HB) are constructed to contain only that part of the surface antigen that is very potent in stimulating the immune system to produce antibodies. The vaccine contains no viral component other than the surface antigen, and therefore, cannot cause HBV infections. Hepatitis B vaccines should be given in three doses with the second dose 1 to 2 months after the first dose, and the third dose 4 to 6 months after the first dose. For the best results, the vaccinations should be given in the deltoid (shoulder) muscles and not in the buttocks.
Hepatitis B vaccines are 95% effective. Five percent of vaccinated individuals will fail to develop the necessary antibodies for immunity after the three doses. Patients with weakened immunity (such as HIV infection), elderly patients, and patients undergoing kidney hemodialysis are more likely to fail to respond to the vaccines.
Hepatitis B vaccine is recommended for:
- All infants
- Adolescents under 18 years of age who did not receive hepatitis B vaccine as infants
- People occupationally exposed to blood or body fluids
- Residents and staff of institutions for the developmentally disabled
- Patients receiving kidney hemodialysis
- People who with hemophilia and other patients receiving clotting factor concentrates
- Household contacts and sexual partners of patients infected with hepatitis B chronically
- Travelers who will spend more than 6 months in regions with high rates of hepatitis B infection
- Injection drug users and their sexual partners
- Men who have sex with men, men or women with multiple sex partners, or recent infection with a sexually transmitted infection
- Inmates of long-term correctional facilities
All pregnant women should have a blood test for the antibody to hepatitis B surface antigen. Women who test positive for hepatitis B risk transmitting the virus to their infants during labor, and, therefore, infants born to mothers with hepatitis B infection should receive HBIG in addition to hepatitis B vaccine at birth. The reason for giving both immunoglobulin and vaccine is that even though hepatitis B vaccine can offer long lasting, active immunity, immunity takes weeks or months to develop. Until active immunity develops, the short-lived, passive antibodies from the HBIG protect the infant.
Unvaccinated individuals exposed to materials infected with hepatitis B (such as healthcare workers stuck by a contaminated needle) will need HBIG in addition to hepatitis B vaccine for the same reason as infants born to mothers with hepatitis B infection.
Hepatitis C and D
There is currently no vaccine for hepatitis C. However, researchers claim preliminary research results suggest that a vaccine can be made that will be effective against the multitude of HCV antigenic types that infect humans. They predict it may become available in about 2 to 4 years. No vaccine for hepatitis D is available. However, HBV vaccine can prevent an individual not infected with HBV from contracting hepatitis D because hepatitis D virus requires live HBV to replicate in the body.