The first available hepatitis B vaccines were plasma-derived, produced by harvesting hepatitis B surface antigen (HBsAg) from the plasma of persons with chronic HBV infection. The particles are highly purified, and any residual infectious particles are inactivated by various combinations of urea, pepsin, formaldehyde and heat. Although concerns about transmission of bloodborne pathogens, including HIV, from plasma-derived vaccines have proven to be unfounded., public concerns over the safety of the plasma-derived vaccine hampered its acceptance in many populations. Therefore increased research efforts were made to develop a recombinant vaccine.
In 1986, a hepatitis B vaccine produced by recombinant technology was licensed, and a second followed in 1989. The recombinant technology expressed HBsAg in other microorganisms and offered the potential to produce unlimited supplies of vaccine.
Although both the plasma-derived and recombinant hepatitis B vaccines are safe and highly effective in protecting against acute hepatitis disease as well as chronic disease, including cirrhosis and liver cancer, competition among the various hepatitis B vaccine producers drove down the price. When the price of both the plasma-derived and recombinant hepatitis B vaccines was relatively similar, the recombinant gradually replaced the plasma-derived hepatitis B vaccine.
Both acellular (aP) and whole-cell pertussis (wP) vaccines are safe and effective. In terms of rare, more severe adverse reactions, aP and wP vaccines appear to have the same high level of safety. However, mild-to moderate adverse reactions are more commonly associated with wP vaccines, and tend to increase with client age and the number of injections. This is why wP vaccines are not recommended for use in adolescents and adults where aP vaccines rather come to use.
Because the price of wP is considerably less than aP, where resources are limited and the vaccine is well accepted by the local population, wP vaccine remains the vaccine of choice. In countries where a higher rate of adverse reactions after immunizations with wP prevents high vaccination coverage, aP is recommended instead, at least for booster injections.
Commonly used protein-based subunit vaccines are the following:
Acellular pertusis (aP) vaccines contain inactivated pertussis toxin (protein) and may contain one or more other bacterial components. The pertusis toxin is detoxified either by treatment with a chemical or by using molecular genetic techniques
Hepatitis B vaccines are composed of the hepatitis B virus virus surface antigen (HBsAg), a protein produced by hepatitis B virus. Earlier vaccine products were produced using purified plasma of infected individuals. This production method has been replaced by recombinant technology that can produce HBsAg without requiring human plasma increasing the safety of the vaccine by excluding the risk from potential contamination of human plasma.
Protein based subunit vaccines present an antigen to the immune system without viral particles, using a specific, isolated protein of the pathogen. A weakness of this technique is that isolated proteins, if denatured, may bind to different antibodies than the protein of the pathogen.
Subunit vaccines, like inactivated whole-cell vaccines do not contain live components of the pathogen. They differ from inactivated whole-cell vaccines, by containing only the antigenic parts of the pathogen. These parts are necessary to elicit a protective immune response
This precision comes at a cost, as antigenic properties of the various potential subunits of a pathogen must be examined in detail to determine which particular combinations will produce an effective immune response witthin the correct pathway
Often a response can be elicited, but there is no guarantee that immunological memory will be formed in the correct manner