Hepatitis B Vaccines: What You Need to Know

Ian Campsall

There are currently five vaccines available to prevent hepatitis B: Hepcare (formerly Hepagene); and Bio-HepB, as well as Energix B, Recombivax HB, and GenHevacB which are recombinant HBV vaccines or, simply put, they operate through using re-sequenced DNA strands taken from the hepatitis B virus. There are also three combination vaccines available: TwinRix for HBV and HAV in adults, Comvax for HBV and the Haemophilus influenza virus (HiB) in children, and Hexavac for HBV, Diphtheria-Tetanus-Pertussis (DTP), HiB, and Polio in children. Dynavax Technology is developing a vaccine which is currently in phase II of development, and PowderJect is working on an HBV DNA vaccine which is currently in phase I.

Routine vaccination against hepatitis B for infants in America was begun in 1991 following a landmark decision by the federal Advisory Committee on Immunization Practices (ACIP). The committee originally gave physicians the option of vaccinating children at birth, or at up to two months of age for infants of hepatitis B surface antigen (HBsAg) seronegative mothers. The vaccine is administered to adults as a series of three injections over six months: the second injection is given one month after the first, and the third five months later. A two-dose vaccine is available for adolescents between the ages of 11 and 15. Currently there are two types of products available in the United States for prophylaxis or vaccination against HBV infection. The Hepatitis B vaccine provides long-term protection against HBV infection and is recommended for both pre and post-exposure treatment.

The program has proved to be remarkably successful with the vaccination coverage of two-year-olds in the U.S. recently reaching 90.3% in 2001, and the number of children infected with acute hepatitis B falling 80% in the ten years since the program began. While immunization against Hepatitis B is the most effective method of preventing infection, this approach has not effectively lowered the incidence of the disease in America primarily because the strategy has been based on selectively vaccinating persons identified as having high risk factors.

According to a study published by the ACIP in September of 1991, inoculating persons who participate in behaviors, life-styles, or occupations known to be high risk before they are infected is not a practical or effective method of preventing the spread of HBV. This is simply because by the time they are identified as being at risk, they are often already infected. Furthermore, vaccinating adolescents and adults is significantly more expensive because of the higher vaccine cost and the higher costs associated with delivering the vaccine to target populations. In the long term, universal infant vaccination would eliminate the need for vaccinating adolescents and high-risk adults and result in substantial savings.

The CDC formulated its strategy for eliminating the transmission of hepatitis B in the United States in 1991 as follows:

A comprehensive prevention strategy includes a) prenatal testing of pregnant women for HBsAg to identify newborns who require immunoprophylaxis for the prevention of perinatal infection and to identify household contacts who should be vaccinated, b) routine vaccination of children born to HBsAg-negative mothers, c) vaccination of certain adolescents, and d) vaccination of adults at high risk of infection.

Both infants and children could be vaccinated during routine medical appointments. This program would be greatly enhanced by the introduction and development of multiple-antigen vaccines such as diphtheria-tetanus-pertussis (DTP)/hepatitis B, and haemophilus influenza type b (HiB)/ hepatitis B. These vaccines would reduce both the number of injections received by the infant and the cost of administration, while greatly facilitating widespread vaccine delivery throughout the United States. It should also be noted that the hepatitis B vaccine prevents other serious consequences of hepatitis B, such as hepatocellular carcinoma (liver cancer), and is, therefore, the first anti-cancer vaccine. Candidates for vaccination include the following:

• People with liver disease, and especially someone with HCV
• People with multiple sex partners and those who have been recently diagnosed with a sexually transmitted disease.
• Sex partners and household contacts of HBV carriers.
• Men who have sex with men.
• Household contacts of adoptees from countries with high rates of hepatitis B.
• Injection drug users (IDUs)
• Travelers to countries with high rates of hepatitis B (staying longer than 6 months).
• People with occupational exposure to blood.
• Clients and staff in institutions for the developmentally disabled.
• Patients with chronic kidney failure (including those on chronic hemodialysis).
• Patients receiving clotting factor concentrates.
• Inmates of long-term correctional facilities.

The duration of vaccine-induced immunity has only been evaluated in long-term follow-up studies for the hepatitis B vaccine manufactured from the plasma of persons infected with HBV; however, similar results can be expected with the recombinant vaccines. Long-terms studies of uninfected adults and children indicate that immunity remains intact for at least nine years, and a recent study in the British Medical Journal (2002; 325 [7364]: 569-70) concluded that “Children vaccinated in infancy are at increased risk of hepatitis B virus infection in the late teens." Nevertheless, booster shots are not recommended for children and adults with a normal immune status, but it is recommended that hemodialysis patients should be given an annual anti-body test to asses the level of anti-bodies present.

The ACIP’s program has been successful thus far, however, the continued success of the strategy came under a cloud in 1999 when a controversy arose over the presence of a mercury-containing preservative, called thimerosal, in childhood vaccines. A thimerosal free vaccine was rapidly produced, but many hospitals and pediatricians had already stopped using the vaccine and refused to re-instate its use. Recently, fears have also arisen regarding the vaccine’s possible connection to multiple sclerosis and other neuromuscular diseases, but it must be stressed that there is absolutely no scientific evidence linking the vaccine to any neuromuscular disease. According to the ACIP, reports of unusual illnesses following vaccines are most often related to other causes, not the vaccine. Furthermore, whenever large numbers of vaccinations are performed, some adverse events will occur coincidentally after vaccination and be falsely attributed to the vaccine.

The ACIP’s original 1991 program could effectively eradicate HBV in America. By vaccinating all children against HBV before they ever are exposed to the virus we could focus all available resources on treating those already infected. The HBV vaccine is simply the best way to protect yourself against this disease, and prevent its continued spread. http://www.immunize.org/

October, 2002 Hepatitis C Support Project. Reprint permission is granted and encouraged with credit to the Hepatitis C Support Project

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