Definition and Types of Vaccine

What is Vaccine?

Vaccine is a substance prepared from dead or living microorganisms that is introduced into the body through inoculation. Vaccinations work by stimulating the immune system to a particular disease.

Types of Vaccine:

There four types of vaccines which are presented in the following:

1. Inactivated (Killed) Vaccines:

This type of vaccines is generated by killing the disease which causing microbe with chemicals, heat or radiation. This destroys the pathogen’s capability to reproduce, but keeps it “intact” so that the immune process can still recognize it. Examples are Influenza, Cholera, Polio, Hepatitis A and Rabies.

2. Live (Attenuated) Vaccines:

Live attenuated vaccines are prepared from live microorganisms or functional viruses whose disease producing capability has been weakened but whose immunologic properties have not. Because, live vaccines are the closest thing to a natural infection, these vaccines are good “teachers” of the immune system. They provide lifelong immune response to vaccinated person against severe disease or even infection with only one or two doses such as Measles, Mumps, Rubella.

3. Toxoid Vaccine:

These vaccines are used when a bacterial toxin is the main cause of illness. Scientists may able to formulate vaccines from just the deactivated toxin, rather than the total bacteria. The immune process produces antibodies that lock onto and block the toxin when the vaccines are administered. Diphtheria and Tetanus are examples of toxoid vaccines.

4. Sub-unit and Conjugate Vaccines:

Sub-unit vaccines are vaccines that use only part of disease causing virus. A vaccine containing viral antigens made free of viral nucleic acid by chemical extraction and containing only minimal a mounts of non viral antigens derived from the culture; it is less likely to cause adverse reactions than vaccines containing the whole vision. Some bacteria have special types of coatings which hide them from the immune system. Conjugate vaccines link these coatings to an organism that an immature immune process can recognize, so that it can respond and produce immunity.