VACCINES

INTRODUCTION: Vaccines have always been developed and used for ages so far. The purpose of vaccines is to prevent disease for known infectious agents and following thorough scientific demonstration and investigations in animal species such as mice, rats, rabbits among others, safer and effective vaccines are developed for prevention of various intended diseases. The safer and effectively developed vaccine against disease X is then used in the human populations to eradicate the disease.

COMPOSITION OF VACCINES: A vaccine contains an antigen that the immune system will respond to, just as it would to the actual pathogen. To look at the antigen more closely, it will have some resemblance to the intended pathogen in order to be able to stimulate the immune system.

TYPES OF VACCINES: The types of vaccine antigens are;

1. A killed or weakened also known as attenuated pathogen,

2. Part of a pathogen such as a bacterial capsule, or an inactivated bacterial toxin called a toxoid.

PATHOPHYSIOLOGY: Because the vaccine itself does not cause disease with very rare exceptions, the fact that antibody production to it is slow is not detrimental to the person. The vaccine takes the place of the first exposure to the pathogen and stimulates production of antibodies and memory cells. On exposure to the pathogen itself, the memory cells initiate rapid production of large amounts of antibody, enough to prevent disease.

EXAMPLES OF VACCINES: We now have vaccines for many diseases. The tetanus and diphtheria vaccines contain toxoids, the inactivated toxins of these bacteria. Vaccines for pneumococcal pneumonia and meningitis contain bacterial capsules. These vaccines cannot cause disease because the capsules are non-toxic and nonliving; there is nothing that can reproduce. Influenza and rabies vaccines contain killed viruses. Measles and the oral polio vaccines contain attenuated (weakened) viruses. Although attenuated pathogens are usually strongly antigenic and stimulate a protective immune response, there is a very small chance that the pathogen may regain its virulence and cause the disease with proper clinical practice.

RELATED;

1.  ACTIVE IMMUNISATION

2.  BCG VACCINATION

3.  PASSIVE IMMUNISATION

4.  ORGANS OF THE IMMUNE SYSTEM

5.  INNATE IMMUNITY

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