Wednesday, December 8, 2021
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What is vaccination?

Vaccination: is a method of passive immunization that aims to help protect individuals against the development of certain potentially serious infectious diseases by injecting a vaccine (vaccination of vaccine). It exposes the vaccinated subject to certain antigens to prepare the organism to defend itself, if the disease occur, by stimulating his immune memory.

What is a vaccine?

A vaccine is a preparation containing microorganisms which are either inactivated or killed germs. This preparation is administered for the purpose of passive immunization of the organism against infectious diseases.

How does a vaccine work?

Vaccines consist of exposure either to a killed or attenuated microbe or, most often, to a single fragment of microbe. This is called antigens (Ag). This allows the body to develop immune defenses against the targeted disease, without being or being very little sick. Thus, if one day the vaccinated individual encounters the real and this time dangerous microbe, the immune system will recognize it and immediately activate itself to protect it from this disease. The immune system makes antibodies to specifically kill this microbe; it is a natural defense mechanism. However, it takes a certain time to react when it encounters a microbe: during this time, it can proliferate and cause serious diseases (meningitis, measles, etc.). On the other hand, when it has already encountered the microbe, it reacts very quickly and immediately blocks the disease. This is what vaccines do. Not all vaccines have the same duration of protection. It is therefore sometimes necessary to carry out vaccination reminders to maintain this memory throughout life.

What is a microbe?

microbes always refer to living organisms that are microscopic, that is, they can only be observed through a microscope. And for good reason, they are 100 to 10,000 times smaller than a grain of sand! In water, on land or in suspension in the air, microbes are able to colonize all environments, including the most extreme, such as the poles or deserts. A considerable number thus live in our intestines, our mouth or on our skin.

A small number of them, however, are pathogens. They are the ones who give the group a bad reputation. They are found in the three main families of microbes:

  • bacteria
  • viruses

Vaccination: What happens in our body when we get vaccinated?

When we fall ill, our body’s defense system, the immune system, fights against a microbe (virus, bacteria, etc.). It manufactures substances to neutralize and eliminate them.

A vaccine contains a small amount or a fragment of bacteria or virus that is either dead or weakened (weakened). These bacteria or viruses are components foreign to the body which will push its defense system to react without causing disease. They are called antigens.

To be vaccinated is therefore to introduce a harmless microbe into our body. It doesn’t really make you sick, but our immune system reacts anyway by producing specific antibodies to fight it off.

If we are subsequently infected with the real microbe, our immune defenses previously activated by the antigens contained in the vaccine recognize it more quickly and can neutralize it before the disease develops. This is “immune memory”.

Vaccination: Why do we need to be reminded of vaccines?

For some diseases, the protection from the vaccine may be reduced over time. The amount of antibodies produced by the vaccine is decreasing. Boosters should therefore be given at a rate that varies from vaccine to vaccine. This recall aims to maintain a good level of protection against the targeted disease. It consists of reinjecting a dose of the same vaccine.

A well-known example is that of tetanus: boosters are needed every 10 years and throughout life. The influenza vaccine, on the other hand, must be renewed each year in people for whom this vaccination is recommended.

Reminders are to be distinguished from catch-ups. Catch-up consists of ensuring complete protection against disease by injecting the missing dose of the vaccine according to the vaccination schedule.

Being up to date with your vaccines means having taken the vaccines recommended for your age and situation and having received the right number of injections to be protected. This protection may not be complete if you have not received all of the recommended doses.

Vaccination: Composition of vaccine

  • Antigens (Ag): a killed or attenuated microbe, or most often a simple fragment of it.
  • Stabilizers: they make it possible to preserve the quality of the vaccine after its production and during its storage. These are sugars (lactose, sucrose), amino acids (glycine) or proteins (albumin, gelatin).
  • Preservatives: they prevent the proliferation of bacteria or fungi that can contaminate the vaccine.
  • Diluents: they are used to dilute the vaccine before injection, it is sterile water or sterile saline solution.
  • Adjuvants: present in all modern vaccines except in live attenuated vaccines (Measles-Mumps-Rubella: MMR) and most influenza vaccines. They stimulate and strengthen the immune system against the microbial antigen. They protect against several diseases with a simple injection. The most widely used adjuvants are aluminium salts.
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