Vaccine
A vaccine is an injection of an antigen designed to create an immunity to a particular disease. The primary mechanism that a body uses to identify infections is a protein molecule called an antibody. If the body has a particular antibody for a particular disease it can identify the infection early on and the immune system can destroy it. Vaccine's work by exposing the body to a form of the disease in such a way that it will not cause illness but allow antibodies to develop. This confers a level of immunity to the organism vaccinated.[1]
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 lines 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 eliminate their effect, antibodies will still be produced to these deactivated toxins. Finally, component vaccines use pieces of the pathogen in the injection. These pieces often of identifying protein segments that allow antibodies to be produced.[2]
Only live attenuated vaccines can still cause infection.The other three types of vaccines can cause illness, but this is an allergic response not due to the disease itself. Very rarely a serious disease known as eczema vaccinatum can emerge. Vaccines that use pieces of pathogens often use a carrier virus in the injection. Those with very weak immune systems that are exposed to such a vaccine can become infected with the carrier virus and develop eczema. A recent case of this was reported in the United States after a father of a military man was vaccinated with small pox and his two year old son became ill. [3]
Since the adoption of vaccination, however, many diseases have been curbed. Polio, for example, killed over 3,000 people in the United States in 1952 [1], and inflicted 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 erradicated the disease in the developed world.
Other diseases that have been curbed since the invention of vaccines include smallpox (previously a yearly killer of thousands worldwide), measles, mumps, rubella, and typhoid.
Influenza Vaccine
The flu vaccine is an excellent example of modern vaccination. Due to changes in the influenza virus, new influenza vaccines are created each year. According to the CDC [4],
Influenza viruses are always changing. Therefore, influenza vaccines are updated every year, and an annual vaccination is recommended.
The tendency of the influenza virus to rapidly change, and the call for revaccination against it, is a prime example of the necessity for preventative measures to be updated with some frequency in order to effectively decrease the incidence of pathogenic afflictions.
References
- ↑ http://www.howstuffworks.com/immune-system7.htm How stuff works: Antibodies
- ↑ http://www.drspock.com/article/0,1510,4866,00.html The Main Types of Vaccine
- ↑ http://www.associatedcontent.com/article/183349/soldier_infects_toddler_son_with_lifethreatening.html AP article on eczema vaccinatum
- ↑ "Inactivated Influenza Vaccine, What you need to know," a publication of the Center for Disease Control, 2006. Available online at: http://www.cdc.gov/nip/publications/VIS/vis-flu.pdf