Robert's HBV Page - Prevention

PREVENTION

Universal Blood and Body Fluid Precautions
All blood and body fluid should be treated as if they contain HIV, HBV and other blood-borne pathogens. Gloves should be used when handling suspicious materials. Hands should be washed regularly. Also, needles and other sharp objects should be handled with extra care to prevent unwanted needle-stick transmission.

Suspected contaminated surfaces should be disinfected and cleaned. Surfaces can be decontaminated using disinfectants such as 0.5% sodium hypochlorite, 2% aqueous alkalinized glutaraldehyde, quaternary ammonium germicides or phenolic-based disinfectants.

Vaccination
Currently, the best method to prevent HBV infection is through vaccination. The most common vaccine on the market is derived from a recombinant yeast source. The small hepatitis B surface protein (SHBs) is generated by yeast cells. Expression of this protein by yeast results in SHBs particle formation. However, particles are not secreted by the yeast. Disruption of yeast cells is performed in order to liberate the produced spheres into solution. These particles are then purified through clarification, ultrafiltration, chromatography, and ultracentrifugation. The purified particles are then adsorbed onto aluminum hydroxide to which thimerosal is added to preserve the solution.

The two yeast-derived vaccines licensed in most countries are Engerix-B (SmithKline Beecham, Philadelphia, PA) and Recombivax HB (Merck & Co., West Point, PA). Both products are structurally and chemically similar with less than 2% yeast protein remaining in solution. Recombivax HB, however, is treated with formaldehyde before its adsorption onto alum. As both are yeast-derived, the S-protein is not glycosylated (as yeast does not possess the correct post-translational machinery to do so). Both, thankfully, appear to be quite effective as vaccines, allowing for immunization against the various forms of HBV. The vaccines, however, should not be frozen as this appears to be deleterious to its immunogenicity. Studies have shown that freezing of these vaccines results in lower immune response.

There are also some other forms of immunization and vaccines, but the ones mentioned above generally appear to be the most effective and the most widely used.

Typical vaccination schedules are 0,1 and 6 months or 0, 1, 2 and 10 months. The 0, 1 and 6 month vaccination schedule is preferred for routine pre-exposure prophylaxis. The four-dose schedule may be preferred, however, for immuno-compromised patients or for postexposure prophylaxis. It has also been recommended that a booster shot be given every 5 to7 years after the initial vaccination. Infants may also be vaccinated this way.

However, there have been some (though rare) reports of adverse reactions to these yeast-derived vaccines. Some possible serious adverse reactions include skin, rheumatic, vasculitic, ophthalmologic, hematologic, and neurologic reactions. In general, the side effects of HBV vaccination are relatively minor such as pain at the injection site (3% to 29%) and temperature greater than 37.7C.

Also, not everyone responds adequately to the first set of vaccination injections. Especially for those working in the health profession or those who are in close contact with someone who is infected, it is advisable to be tested about a month or so after the final vaccination to ensure antibody titres are high enough.

There has been a recent surge in development of new hepatitis B vaccines made of the large and small hepatitis B surface proteins or DNA vaccines or even combination vaccines such as a vaccine providing dual protection against hepatitis A and B (Twinrix, SmithKline Beecham Biologicals).

Post-Exposure Immunoprophylaxis
Though not generally used, there are some cases in which an individual may definitely benefit from an administration of anti-HBs antibodies. These types of individuals include those who are not vaccinated, but who may have been exposed to live virus through sexual contact, transient exposure to contaminated material or fetuses/neonates of infected mothers.

Timing of the initial dose of the prophylactic antibody appears crucial and effectiveness diminishes significantly if delivery is delayed more than three days post-exposure.

References

Bond, W.W., Favero, M.S., Petersen, N.J. and Ebert, J.W. 1983. Inactivation of Hepatitis B Virus by Intermediate-to-High Disinfectant Chemicals. J. Clin. Microbiol.; 18: 535-538.

Davis Hl, Mccluskie Mj, Gerin Jl, Purcell Rh. 1996. Dna Vaccine For Hepatitis B: Evidence For Immno-Genicity In Chimpanzees And Comparison With Other Vaccines. Proc. Natl. Acad. Sci. Usa; 93: 7213-8.

Ellis, R.W. 1993. Hepatitis B Vaccines in Clinical Practice. New York: Marcel Dekker.

Grotto, I., Mandel, Y., Ephros, M., Ashkenazi, I., and Shemer, J. 1998. Major Adverse Reactions to Yeast-Derived Hepatitis B Vaccines -- A Review. Vaccine; 16: 329-334.

Hauser, P., Thomas, H.C., Waters, J., et al. 1988. Induction of Neutralising Antibodies in Chimpanzees and in Humans by a Recombinant Yeast-Derived Hepatitis B Surface Antigen Particle. In: Zuckerman, A.J. ed. Viral Hepatitis and Liver Disease. New York: Alan R. Liss: 1031-1037.

Hoofnagle, J.H. 1987. Antiviral Tratment of Chronic Type B Hepatitis. Ann. Intern. Med.; 107: 414-415.

Mosley, J.W. 1979. Hepatitis B Immune Globulin: Some Progress and Some Problems [Editorial] Ann Intern Med; 91: 914-915.

OSHA. 1991. Occupational Exposure and Bloodborne Pathogens: Final Rule. Dept. of Labor, 29 CFR Part 1910, 1030. Federal Register; 56: 64175-64182.

Ostros, D.G., Goldsmith, J., Kalish, S.B., Chmiel, J.S., Hadler, S.C. and Phair, J.P. 1987. Nonresponse to Hepatitis B Vaccine in Homosexual Men. Sex. Transm. Dis.; 14: 92-97.

Sehulster, L.M., Hollinger, F.B., Dreesman, G.R. and Melnick, J.L. 1981. Immunological and Biophysical Alteraction of Hepatitis B Virus Antigens by Sodium Hypochlorite Disinfection. Appl. Environ. Microbiol.; 42: 762-767.