Next, lymphocytes called T and B cells are manufactured specifically to target a specific type to pathogen. These B and T cells remain in the blood stream for years, thus, preventing that particular pathogen from causing disease in the future (Cowan 426-432). .
Vaccines work much like synthetic pathogens in order to stimulate B and T cell production. The twelfth edition of the book, Epidemiology and Prevention of Vaccine-preventable Diseases, revised in 2012, written by epidemiologist, William Atkinson discusses the mechanics of vaccines in the immune system. According to Atkinson, there are three types of vaccines: live attenuated vaccines, inactivated vaccines, and polysaccharide vaccines (5-7). Live attenuated vaccines contain an extremely weakened, non-pathogenic version of disease causing pathogens. Inactivated vaccines contain non-living or inactivated versions of pathogens. Polysaccharide vaccines contain the surface proteins of pathogens (Atkinson 5-8). Each type of vaccine interacts with the immune system in a slightly different manor in order to stimulate and develop immunity to disease. .
In order for vaccines to be effective at preventing epidemics, the majority of the public must posses vaccine related immunity. This concept of general public immunity is termed as herd immunity. The Centers for Disease Control and Prevention explains that herd immunity occurs when a large number of community members are vaccinated and immune to disease, thus, are able to protect those who are not immune by preventing the spread of disease amongst the community (Centers web). In the 2011, Oxford Journal article, ' 'Herd Immunity'': A Rough Guide, written by researcher, Paul Fine and colleagues, the theory of herd immunity is discussed and tested. According to Fine, at least 80% of a population must be vaccinated in order for herd immunity to be effective (914). Prospectively, it is imperative that vaccines are distributed to as many individuals as possible in order to protect those who are unable to receive them.
