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[[Image:Vaccine.jpg|right|thumb|350px|[[Avian flu]] vaccine development]]

[[Image:Vaccine.jpg|right|thumb|350px|[[Avian flu]] vaccine development]]

A '''vaccine''' is an pharmaceutical product containing an [[antigen]] designed to stimulate the production of antibodies abainst a particular disease or diseases.<ref>https://www.sciencenewsforstudents.org/article/explainer-what-vaccine</ref>

A '''vaccine''' is a pharmaceutical product containing an [[antigen]] designed to stimulate the production of antibodies against a particular disease or diseases.<ref>https://www.sciencenewsforstudents.org/article/explainer-what-vaccine</ref>

If the body produces an antibody against a particular disease or toxin it can identify the infection early on and the [[immune system]] can destroy it. Vaccines work by exposing the body to a form of the disease in such a way that it is much less likely cause illness but still allows antibodies to develop. This confers a level of immunity to the organism vaccinated.<ref>http://www.howstuffworks.com/immune-system7.htm How stuff works: Antibodies</ref>

If the body produces an antibody against a particular disease or toxin it can identify the infection early on and the [[immune system]] can destroy it. Vaccines work by exposing the body to a form of the disease in such a way that it is much less likely cause illness but still allows antibodies to develop. This confers a level of immunity to the person or animal vaccinated.<ref>http://www.howstuffworks.com/immune-system7.htm How stuff works: Antibodies</ref>

There are four major types of vaccines and they are differentiated by what antigen is used. Live attenuated vaccines are created from the actual disease in question, however before injection the [[pathogen]] is [[attenuated]] (weakened) by growing successive generations of the pathogen in poor nutrient conditions. It is possible for these vaccines to still cause an infection. Inactivated vaccines are created from pathogens that have been killed, usually with the use of a preservative [[formaldehyde]]. Toxoid vaccines are created by using toxins produced by the pathogen, before injection these toxins are exposed to heat and chemicals that inactivate the toxins, but [[antibodies]] that are produced to these deactivated toxins will also protect against the real toxin. Finally, component vaccines use pieces of the pathogen in the injection. These pieces often consist of unique protein segments that stimulate the production of antibodies.<ref>http://www.drspock.com/article/0,1510,4866,00.html The Main Types of Vaccine</ref>

There are five major types of vaccines and they are differentiated by what type of antigen is used. Live attenuated vaccines are created from the actual disease in question, however before injection the [[pathogen]] is [[attenuated]] (weakened) by growing successive generations of the pathogen in poor nutrient conditions. Because they contain live pathogens, it is still possible for these vaccines to cause infection, particularly in imunnocompromised individuals. Inactivated vaccines are created from pathogens that have been killed, usually with [[formaldehyde]]. Toxoid vaccines are created by using toxins produced by the pathogen, these toxins are exposed to heat and/or chemicals such as formaldehyde to inactivate the toxins, but [[antibodies]] that are produced to these deactivated toxins will also protect against the real toxin. Subunit vaccines use pieces of the pathogen in the vaccine. These pieces often consist of unique protein segments that stimulate the production of antibodies. Finally, conjugate vaccines protect against bacteria that are encapsulated in  polysaccharides (complex sugars), which disguise the bacteria, making it hard for the immune system to recognize them. cungugate vaccines overcume this by attaching the sugar to an antigen

Since the adoption of mass vaccination programs, many diseases have been curbed. [[Smallpox]], a deadly disease responsible for the deaths of millions, has been entirely eliminated through vaccination, excepting some strains maintained for research. Responsible for an estimated 300 to 500 million deaths worldwide in the 20th century, vaccination programs of the 19th and 20th century were effective at curbing the disease, and in 1979 the World Health Organization declared smallpox to be eradicated.

Since the adoption of mass vaccination programs, many diseases have been curbed. [[Smallpox]], a deadly disease responsible for the deaths of millions, has been entirely eliminated through vaccination, excepting some strains maintained in labs for research or weapons purposes. Responsible for an estimated 300 to 500 million deaths worldwide in the 20th century, vaccination programs of the 19th and 20th century were effective at curbing the disease, and in 1979 the World Health Organization declared smallpox to be eradicated.{{cn}}

[[Polio]], for example, killed over 3,000 people in the United States in 1952 [http://www.cdc.gov/nchs/data/vsus/VSUS_1952_2.pdf], and afflicted such noted persons as President [[Franklin Delano Roosevelt]], actor Alan Alda, and musician Itzak Perlman. When doctors began using a vaccine to fight polio, it practically eradicated the disease in the developed world.

[[Polio]], for example, killed over 3,000 people in the United States in 1952 [http://www.cdc.gov/nchs/data/vsus/VSUS_1952_2.pdf], and afflicted such noted persons as President [[Franklin Delano Roosevelt]], actor Alan Alda, and musician Itzak Perlman. When doctors began using a vaccine to fight polio, it practically eradicated the disease in the developed world.