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Immunity and Vaccines

By Army Medicine. Licensed under CC BY 2.0


What is Immunity?

It is the ability of the body to resist disease-causing microorganisms and the effects of substances they produce. Viruses, bacteria and other but not limited to unicellular living organisms are treated as foreign substances and whenever they invade the body, it responds by developing a defense mechanism against them. This is referred to as immunity. It works to protects the us from antigens. Ther are to ways to accomplish this role:

1. Special proteins called antibodies are produced. They can clump them together thus preventing them from reproducing, secrete antitoxins to neutralize their poison, dissolve their plasma membrane or adhere to their surface to enable white blood cells to engulf and destroy them.

2. Activation of memory cells type T and B. They can identify antigens in subsequent attacks and thus put in place structures to handle them in future.

In comparison to adults, children have stronger immune systems due to high number of T cells, a type of lymphocyte that responds to microbes produced as the child adapts to new environment. When the child grows, fewer memory cells are produced and if the surrounding does not change a great deal then the strength of the immunity goes down. That is the reason why elderly persons are more at risk than young people. However, it should be noted that age factor is not a reason to neglect any recommendations from medical practitioners. Immunity is either innate, that is, acquired by the body itself when exposed to pathogens or adaptive, vaccine - induced.


Active Immunity

It is developed through contact with microbes. The body mounts up a primary response. Any other similar infections triggers memory cells to recognize them and "counter attack" them. It takes time build but becomes robust thereafter. Naturally, it sets up when an individual is exposed to germs. It is effective for along time and does not easily become weak. Artificially, it is induced by weakened or dead organism when introduced into the body in form of a vaccine. It causes the system to initiate the defense process.

Passive Immunity

Involves transfer of antibodies from one organism to another. This type is preferred where the disease compromises the protection strategy and spreads faster. It might take too long for internal mechanism to bring forth a substantial reaction. In mother-to-child transfer, there are two ways a child can obtain this protection ;

  • When maternal antibodies pass through the placenta into the foetus during gestation period.
  • Through breastfeeding.

Another way involves obtaining shield from one person or animal to another. Antibodies come inform of :

  • Blood plasma
  • immunoglobulin-containing products


It is a substance that stimulate the body to produce antibodies and confer guard against diseases.


1. Inactivated - These are simply organisms whose ability to interfere with the functioning of body is disabled by either heating or exposing them to toxins. As a result, individuals who are injected or orally receives them will not show the symptoms of the disease. However, they still have the same impact of stimulating the system to produce antibodies. Examples of inactivated vaccines are ; whooping cough vaccine, Flu, Hepatitis A and rabies vaccine.

2. Attenuated - They are composed of weakened microbes.

Due to the outbreak of highly infectious diseases such as covid-19, HIV/Aids, Tuberculosis and Hepatitis, it's important to understand the role of immune system and vaccines in order to take the right step towards protecting yourself and family. Vulnerability to infections may not be fully understood until when one is exposed to causative agents. The response to antigens by the body underscores the strength of immunity then and in future. Do not take chances, take control.





This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.


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