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Immunisation, Vaccination And Inoculation: What’s The Difference?

The terms immunisation, vaccination and inoculation have become a part of our day-to-day vocabulary since the beginning of the COVID-19 pandemic in December 2019. Often times these words are used interchangeably, but are they the same? Let's go to the basics and try to understand what these words mean.


What Is Immunisation?

According to the Centers for Disease Control and Prevention (CDC), it's the "process by which a person becomes protected against a disease through vaccination."[1]

In short, immunisation is the process where your body develops resistance or immunity against harmful diseases after administering a vaccine. Children are vaccinated from a very young age in order to develop immunity; BCG vaccine is given at birth to develop immunity against tuberculosis, oral polio vaccine is given at different stages within the first year birth, and TT vaccine is given between the ages 10-16 in order to develop immunity against tetanus. Most of the children in India are also immunised with other important vaccines such as Hepatitis B vaccine, Pentavelant, Rota Virus Vaccine, Measles vaccine [2] [3].

A person can acquire immunity naturally by exposing to the disease causing pathogens and then letting the body develop antibodies to fight the disease. But the modern meaning of immunisation is the administration of vaccine to develop immunity against a disease. Vaccination works the same way as immunising someone by exposing to a pathogen, expect the person develops immune response without getting the disease.

It takes approximately two weeks for an immune response to work, which means your body will not develop immunity immediately after a vaccination or immunisation. Also, many immunisers need several doses for it to be effective; in the case of COVID-19 a booster vaccine is given 12-16 week after the dose.

Immunisation against a disease is not life-long. While some vaccines such as tetanus vaccine can last for 30 years, some such as the influenza vaccine is required to take every year [4].

So, a vaccine helps you develop immunity against a disease. Now let's talk about vaccination.

Photo courtesy: freepik


What Is Vaccination?

According to the CDC a vaccine is "a product that stimulates a person's immune system to produce immunity to a specific disease, protecting the person from that disease [5]."

A vaccine can be injection shots, pills, nasal sprays or liquids-all serve the purpose of teaching your body's immune system to recognise and defend against any disease agent. We know disease agents as viruses such as the COVID-19 and flu virus, or bacteria such as the Mycobacterium tuberculosis that causes tuberculosis and Vibrio cholera that causes cholera.

Vaccines protect us against most of these life-threatening diseases. A vaccine would help people develop immunity against a specific disease- which is far safer for a person and the community-compared to developing immunity by infecting with the disease.

The act of employing a vaccine to human body to help it stimulate the immune system is called Vaccination. Just like how many of us are waiting for our chance to get vaccinated so that we can be immune to the corona virus and its many variants.

Vaccination is a very old mechanism against infectious diseases. The principle of vaccination is said to have began by Asian physicians against small pox. The first vaccine was developed in1796 against smallpox by British physician Edward Jenner who used cowpox virus to grant protection against smallpox. Since then we have prevented viruses and bacteria deadlier than the coronavirus with effective vaccinations throughout history.

There are several types of vaccines:

  • Inactivated vaccines: This vaccine type uses the killed version of the pathogen that causes the disease. Covaxin developed by Bharat Biotech examples of inactivated vaccines.
  • Live-attenuated vaccines: Uses a killed or a weakened form of the germ that causes the disease. Smallpox and chickenpox vaccines are examples.
  • Messenger RNA (mRNA) vaccines: This type makes proteins in order to trigger an immune response. The Pfizer and Moderna COVID vaccines are mRNA vaccines.
  • Subunit, recombinant, polysaccharide, and conjugate vaccines: This type uses parts of the germ like its protein or sugar. Novavax COVID-19 vaccine is an example.
  • Toxoid vaccines: This types a uses the disease causing toxin created by the pathogen. Diphtheria and tetanus vaccines are examples.
  • Viral vector vaccines: This type uses modified version of a different virus to create an immune response. Johnson & Johnson COVID-19 vaccine and Oxford AstraZeneca are examples of viral vector vaccines [6].
  • Photo courtesy: freepik


What Is Inoculation?

Many vaccines such as live-attenuated vaccines and inactivated vaccines use the killed or weakened form of the germ, and when you implant it in a person it is called inoculation.

Better explained, inoculation is any method of vaccination that implants a microorganism-such as a virus or a bacterium-in a person or an animal to grant resistance to a specific disease.

To inoculate mean ‘to graft' in Latin-it means to graft a bud. In the early 18th century, inoculation was the word used for immunising individuals. Small pox was the first disease humans were inoculated against and hence the word inoculation is often used in association with the disesase. It was referred to as variolation before 1800- variola being the name of the virus that causes smallpox. Inoculation as a method against smallpox is believed to have been originated in China in the 15th century. It is also mentioned in the ancient Ayurvdic texts from India [7].

To Conclude

And now, let's put things into perspective. Imunisation is about helping the body develop immunity or resistance against a specific disease. Vaccination is the process through which immunity is granted. And the method of vaccination is inoculation. Hope this helps better understand immunisation, vaccination and inoculation.

Photo courtesy: freepik

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