About Vaccine

A vaccine is a substance that is used for the production of antidotes in the body and provides immunity against one or a few diseases. In biological terms, a vaccine is defined as a biological and formulated preparation to provide acquired immunity for a particular disease. 

Generally, a vaccine is an agent which contains a weakened or killed form of the disease-causing agent, its surface, or its toxins. When this solution is introduced to the human body, the immune system is able to identify the threat and destroy it. More than this, the human body will recognize the threat and can initiate an appropriate response in the future also.


The process of implementing the vaccine is called vaccination. It is responsible for the clearance of many diseases, especially infectious diseases like smallpox and chickenpox. The word "vaccine" is derived from the Latin word "vaccines" which means "from the cows".

Invention of Vaccine

The practice of immunization of the body dates back hundreds of years, but the first official vaccination was developed by Edward Jenner who is considered the founder of vaccinology. In 1796, he injected a 13 year-old-boy with cowpox(vaccinia virus) and established immunity to smallpox. In 1798, the very first smallpox was developed. During the 18th and 19th centuries, systematic implementation of mass smallpox immunization culminated in its global establishment in 1979.

Types of Vaccines

There are many initiations to vaccine development, but vaccines can be mainly classified by how the antigen, active component, that produce a specific immune response against the disease-causing organism, are prepared.

Classification of Vaccines

A. Live Attenuated Vaccines:

Attenuated vaccines are developed in many several ways. The common methods include passing the disease-causing virus through a series of cell cultures or animal embryos. When the vaccine virus is implemented in a human, it will be unable to replicate enough to cause illness, but still promotes an immune response that can protect against future infection.

B. Inactivated Vaccine:

Vaccines of this category are developed by inactivating a pathogen, typically using chemicals or even heat such as formaldehyde or formalin. This destroys the pathogen's ability to replicate but keeps it intact so that the immune still remembers it.

C. Toxoid Vaccine:

There are some bacterial diseases that are not directly caused by a bacteria itself, but by producing toxins by the bacterium. For this type, immunization of pathogens can be developed by inactivating the toxin that causes disease symptoms. As the viruses or organisms used to kill or inactivate vaccines, this can be done through treatment with a chemical such as formalin or by heat.

D. Subunit Vaccine:

Subunit vaccines are only used as part of a target pathogen to promote a response from the immune system. This can be done by isolating a specific protein from a pathogen and presenting it as an antigen on its own.

E. Conjugate Vaccine:

Conjugate vaccines are somehow similar to recombinant vaccines, they are made up of a combination of two different components. Conjugate vaccines, however, are made up of using the pieces from the coat of bacteria. These coats are chemically linked to a carrier immune protein, and this is how a combinational vaccine is used.

F. Valence Vaccine:

Vaccines may be monovalent. The monovalent vaccine is designed to be immune against a single microorganism or single antigen. A multivalent or polyvalent vaccine is made to immunize against two or more viruses of the same microorganism.

G. Heterotypic Vaccine:

Heterologous vaccines are also called "jennerian vaccines". These vaccines are pathogens of different animals that either do not cause disease or cause disease or cause mild disease in the organism being treated.

H. mRNA Vaccine: 

An mRNA Vaccine (or RNA Vaccine) is a different type of vaccine which is a combination of nucleic acid RNA, packaged within a vector such as lipid nanoparticles. 


Vaccination is a process involving introducing deactivated/ weakened disease-causing microbes into a person, or a vaccine is administered to a person to generate immunity from that disease. Vaccination is generally injected or administered orally. It is the drug (weak pathogen/ inactivated) that is administered to a person to prevent the onset of a disease.

Uses of Vaccination

Vaccines are very important because they protect us from infectious diseases. In some areas or populations, infectious diseases are endemic. For example, cholera, polio, smallpox, hepatitis B and so long. To fight against these diseases, we need vaccines to boost our immune systems and prevent harm.

What is an Immunization?

It is the ability of the human body to produce an immune response either naturally, or through vaccines. These approaches develop immunity or resistance to a specific illness. Immunization can be defined as the process by which a person is made to fight against a particular disease by the administration of a vaccine. The basic principle of immunization is that the human body starts to produce antibodies against disease through vaccines so that the person is safe from the infectious disease. The body repeats the process of development of infectious agents and memory cells that can develop antibodies immediately upon further exposure to the infectious agent.

Process of Immunization

  • The process begins when a person is injected through the vaccine and then their bodies begin to develop immunity to fight against the disease.

  • The body generates immunity through this vaccine for the disease rabies.

  • This method has proven to be very effective to prevent a number of infectious diseases.

  • Smallpox, Tetanus, measles, and other diseases have vaccines.

FAQs (Frequently Asked Questions)

Q1. What is a Vaccine?

Ans. A vaccine can be defined as a substance that is used to boost the production of antibiotics, which provides immunity against diseases.

Q2. Name the Types of the Vaccine?

Ans. There are generally 8 types of vaccines developed to date, which include:

  • Inactivated vaccine

  • Attenuated vaccine

  • Toxoid vaccine

  • Subunit vaccine

  • Conjugate vaccine

  • Valence vaccine

  • Heterotypic vaccine

  • mRNA vaccine