By Anele Ngwenya


For centuries, immunisation has been recognised as a very useful tool in mankind’s fight against illness and disease. One of the earliest iterations of this practice is that of the Buddhist monks who would drink snake venom to render themselves immune to their bite. In China, as long ago as the 16th century, physicians would inoculate people with the smallpox virus to help provide immunity. However it was not until 1796 when an English physician, Edward Jenner, published works detailing how he managed to successfully inoculate a 13 year old boy with the cowpox virus (vaccinia) who then later proved to be immune to smallpox. Over time, other prominent scientists such as Louis Pasteur “perfected” this practice and helped launch widespread immunisation drives that eventually led to the eradication of the deadly virus smallpox. Other vaccines such as the Bacillis-Calmette-Guerin vaccine, popularly known as the BCG vaccine (used to immunise against TB) were developed in the late 19th and early 20th centuries and is still in use today. The polio vaccine was another landmark achievement in vaccinology. Development of the Salk and Sabin polio vaccines and their subsequent mass distribution led to the eradication of polio in most parts of the world. Nowadays, there are vaccines for a whole host of potentially deadly diseases such as diphtheria, influenza and measles which are routinely given to people to prevent these diseases.

A lot of us have this scar that signals a successful BCG immunisation. Source:

So how do these vaccines work?

Normally, when your body’s immune system identifies a pathogen (virus, bacteria etc.) it launches an attack on these invaders and in most cases destroys it. The immune system also logs this particular invader in its ‘memory’ so that the next time it invades, the response will be even swifter. The function of vaccines relies on this system.

The vaccine itself is usually comprised of the pathogen in question in a weakened or even killed state. Alternatively, it could be made of proteins unique to the pathogen that would be recognised by the immune system as foreign. The pathogen in the vaccine is therefore not strong enough to cause serious illness in the individual. Instead it trains the immune system to recognise the particular germ, log it in its memory, and quickly destroy it if the individual is ever exposed to it again.



When the COVID-19 pandemic began to disrupt lives all over the globe, there were calls from medical professionals and the rest of the world alike for a cure or a vaccine that would provide a bit of respite from the loss of life, and indeed livelihoods, imposed upon us by the novel coronavirus. Leading pharmaceutical and biotechnology companies have been working hard to find these vaccines with several COVID-19 vaccines in the pipeline. To date, 2 have been approved for production and distribution, the Pfizer BioNTech COVID-19 vaccine and Moderna’s COVID-19 vaccine, while several others are in the last stages of clinical trials. Rollout of the vaccine has already begun, and at the time of writing several countries all over the world have inoculated large numbers of their populations, beginning with the more at-risk groups (the elderly, medical personnel etc.)

Previous articles in this series have already illustrated how the coronavirus attacks the body and also how the body fights back. The COVID-19 vaccines, like all others, helps in making the process of fighting the coronavirus quicker and therefore protecting the person from getting ill. There are a few different types of these vaccines, but the Pfizer BioNTech and Moderna vaccines are both classified as mRNA vaccines. mRNA vaccines do not actually contain the virus, killed or otherwise. Instead they contain instructions for our own cells to make parts of a protein unique to the virus that would also trigger an immune response ( These instructions are destroyed by the cells once the protein has been made.

In the case of the COVID-19 mRNA vaccines, they contain instructions for our cells to make part of the protein that give the virus its characteristic spiky appearance. These spikes cause the immune system to recognize the virus as alien and trigger an immune response. This means that when the person that has been vaccinated comes into contact with coronavirus, the immune system would already recognize the spikes and quickly destroy the virus before the person gets sick. It is worth mentioning that at no point does the mRNA vaccine interact with the nucleus, so it can not alter our DNA, contrary to some myths.

The coronavirus vaccines, like all medicines and vaccines, undergo rigorous testing and are heavily scrutinized before being cleared for mass distribution. They have to demonstrate a high degree of safety and efficacy in order for them to be used. Vaccination has been a major tool in the eradication of diseases like polio and smallpox, and hopefully it will help put an end to the COVID-19 pandemic as well.


  1. Immunisation Advisory Centre. 2021. A Brief History Of Vaccination. [online] Available at: [Accessed 18 January 2021]
  2. Centers for Disease Control And Prevention. 2021. COVID-19 And Your Health. [online] Available at [Accessed 14 January 2021]
  3. [Accessed 20 January 2021]
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