Vaccine – All you need to know about

Amid this pandemic, you might have heard a lot about vaccines. And I am sure you might have thought what exactly is a vaccine, how does it work? Or are vaccines really effective?

In a society where people are starting to question the effectiveness of vaccines and are segmenting themselves as a pro or anti-vaccine, I think there is a strong need for the society to understand it better from how it started, the mechanism and the end result. 


Back in 1796, vaccines came in origin. Edward Jenner is the founder of vaccinology and Father of immunity. He established the process of vaccination by introducing fluid from a cowpox vesicle on a milkmaid into the arm of a boy. He observed that the cowpox material creates immunity towards smallpox which was incurable at that time and somehow death was inevitable. He tried this procedure on another person and got success. He gave the term vaccination for this process. His method underwent many medical and technological developments over the next 200 years, which eventually resulted in eradication of smallpox from the whole world.

Louis Pasteur’s developed live attenuated cholera vaccine(1897) and inactivated anthrax vaccine(1904) in humans. He also prepared vaccines for chicken cholera and rabies. He is also known as ‘Father of immunology’.

Von Behring discovered the process of passive immunization and is known as ‘Father of passive immunization’; prepared the anti diphtheria serum (ADS) by injecting diphtheria antigen into sheep.


vaccine vaccination child baby doctor injection pediatrician injecting arm health immunization hand hospital needle syringe concept – stock image

According to Oxford, vaccines are substances that stimulate the production of antibodies and provide immunity against diseases. These are prepared by various methods like from the causative agent of the disease, its product, or a synthetic substitute, treated to act as an antigen without including the disease.

Vaccination is a simple, safe and effective way of protecting us against lethal diseases. It basically uses our body’s immune system or natural defenses to build resistance to specific infections and prepares your immune system to fight. Vaccines act as trainers for our immune system to create antibodies, same as the way it happens in case of infection happened naturally. Vaccines, however, contain only killed or attenuated germs like virus or bacteria.

The principle of vaccination is based on the property of ‘memory’ of the immune system. The vaccine also produces memory – B and -T cells that recognize the pathogen on subsequent exposure and produces antibodies against it.




These vaccines use attenuated or weakened forms of germ that causes a disease. Here the pathogenicity of the pathogen is only reduced while still keeping it viable. This becomes harmless or less virulent. Some examples of these are smallpox (the first-ever vaccine), BCG ( Bacillus Calmette Guerin), MMR( Measles, Mumps, Rubella), Rotavirus and OPV ( Oral Polio Vaccine, Sabrin Type 1)


These vaccines use the killed or inactivated version of the germ that causes a disease. However, inactivated vaccines do not always create such a strong or long-lasting immune response as live attenuated vaccines. Some examples are Salk polio (IPV), Whooping cough, TAB for typhoid, Rabies, Influenza, Pneumonia and Cholera.


Toxoid vaccines use a toxin, harmful product made by the germ that causes a disease. They create immunity to the parts of the germ that causes disease instead of germ itself. It is capable of instructing the immune system to develop antibodies to activated toxins. Some examples are Tetanus (TT), Diphtheria (DT), Botulism.



Recombinant DNA technology has allowed the production of antigenic polypeptides of pathogens in bacteria or yeast. Vaccines produced using this approach allows large scale production and hence greater availability for immunisation, e.g., Hepatitis- B vaccine produced from transgenic yeast.



DNA vaccines include direct injection of plasmid containing the encoding gene of the considered antigen, which is expressed in the cells with the aid of a specific promoter that causes induction of the immune system. So instead of inserting any plasmid, a vaccine will be produced in the body itself.


According to WHO, vaccines give us immunity to a disease without falling ill. They are made by any of the above mentioned methods. It’s much safer to get a vaccine than to get a disease which prevents it. Vaccine may be taken orally or injected to provide immunity for the pathogen.

  • When a vaccine is injected, it activates our immune system and primary response (mild response) occurs and memory -T and -B cells get activated.
  • On subsequent exposure to the same pathogen or when real infection happens, secondary response/ anamnestic response occurs which helps us to fight infection in no time.
  • This secondary response is based on memory of the primary response caused by injecting vaccines.


      The whole world is in the middle of the pandemic and in terror of coronavirus. Making vaccine for virus is quite tough as it mutates at faster rate than other pathogens. According to WHO, as of 20 February 2021, at least seven different vaccines across three platforms have rolled out in countries. Vulnerable populations in all countries are the highest priority for vaccination. At the same time, more than 200 additional vaccines are under development. From these, more than 60 are in clinical development (WHO data). COVAX is part of the Act Accelerator, which WHO launched in 2020.

       In India, the COVID vaccine was launched on 16th January 2021. The first group includes healthcare and frontline workers. The second group to receive COVID 19 vaccine will be people over 50 years of age and persons under 50 years with comorbid conditions. But we should not be careless thinking that a vaccine has arrived. Even after receiving the COVID- 19 vaccine, we should continue to take all the necessary precautions.

Go take your dose of vaccine during your turn. Do share with us about your experience with vaccines and share your views and experiences in the comments section below.

            Stay tuned for many such informative insights on dynamic topics.