Types of Vaccines

Lecture 4 Types of Vaccine

Whenever an Antigen(Foreign agent- bacteria, virus, fungi, etc.) attacks our body, Antibody Fought war against the Antigen.  

In other words- Antibody is the army of our body. And the job of the vaccine is to train antibodies about the weakness of foreign invaders(Antigen). Vaccines did not fight with foreign invaders, they just trained our antibodies to fight against antigen. Vaccines play the role of a trainer.
In corona time you may encounter different terms like- mRNA vaccine, Conjugated vaccine, inactive vaccine etc. In this post we will clarify all types of vaccines.

There are two types of vaccine based on targeted action point-
1. Antigen vaccine- The vaccine trains our antibody to fight against antigen

2. Toxoid vaccine-  The vaccine trains our antibodies to fight against the weapon of antigen. The main target of the antibody was not the antigen but the toxin product released by antigen. Toxoid vaccine- Tetanus vaccine(caused by bacteria), Diphtheria vaccine(caused by bacteria)

Three types of Antigen Vaccines

1. Unit vaccine- The Inactive(Dead) or Attenuated(weak) Antigen is used in vaccine manufacturing. As Attenuated antigen are more similar to living antigen, Attenuated Vaccine provides immunity for a longer period of time.(Inactive- quick booster dose)

2. Subunit vaccine- Only a part(Polysaccharide/Sugar or Protein) of the Antigen is used in vaccine manufacturing. The vaccine trains our antibodies to attack on a specific portion of antigen. Instead of firing bullets all over the body, one head shot is enough.
As in subunit vaccines the attack is targeted one so subunit vaccines are good for people with weak immunity(low antibody count etc).
Conjugated vaccine is a variation of Polysaccharide vaccine. Where the Polysaccharide of target antigen is used with protein of other antigen- This is used to develop a stronger immunological response.

3. Genetic vaccine(Nucleic acid vaccine)- Only the genetic code of the Antigen is used in vaccine manufacturing.
In viral vector vaccines the genetic code of targeted antigen is used in combination with a virus(generally virus that does not harm human health). In this the virus only plays the role of delivering the genetic code of foreign antigen to our body.
Genome- All genetic information of an organism in sequence.
In genetic vaccines a gene of specific location of antigen is used, so it attacks only that portion of antigen with which the gene is associated. So it works in a similar fashion like subunit vaccine- targeted attack(good for people with weak immunity).


For the development of unit and subunit vaccines, artificial culturing of targeted antigen is required. Which is time consuming.
While genetic vaccines can be developed in a short span of time, once the genetic information of targeted antigen is available.

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