Vaccines: What They Are & How They Work

This Article was written by Salvador Ampuero, Year 13


As we speak, the world is in the midst of the Covid-19 pandemic; dealing with the unforeseen challenges caused by ‘coronavirus’ that has taken a significant toll on individuals all around the world. At the time of writing this article, there have been over 100 million confirmed cases across over 221 countries and territories, which has left the entire population of the world with uncertainties and questions- such as ‘when will this end?’ and ‘what will our lives look post-pandemic.’

However, as there is no definitive answer to these questions, it is important for everyone to remain safe in the situation at hand as we wait for herd immunity to be achieved.


This article will talk you through everything you need to know about vaccinations & how they are effective:



Herd immunity is a biological term for when a sufficiently large percentage of the population is immune to a specific disease, which prevents the spreading of that disease (or dramatically reduces the likelihood) within the population.

Think of when it’s raining- with bacteria being the raindrops. When you get vaccinated you put on a raincoat, which protects you from the raindrops, but the best way to protect yourself is using a raincoat and an umbrella- with the umbrella being all the individuals around you also being protected. Herd immunity is necessary as it not only protects you and your family, but it protects other individuals who cannot be vaccinated, due to varying conditions; such as age restrictions or because their immune system is compromised.



Fortunately, due to the advances in medical technology, an emergency Covid vaccine was rapidly manufactured by a variety of countries and companies. Creating a vaccine in under a year was a monumental task. However, the Covid-19 pandemic established a new norm for social distancing and wearing masks, whilst simultaneously catalysing global cooperation for vaccine development and distribution. Researchers are currently testing 67 vaccines in clinical trials in humans, with 20 having reached the final stages of testing. Furthermore, over 89 pre-clinical vaccines are under investigation on animals.

There are two main types of vaccine circulating the world as of this moment, which provide immunity in two different ways - ‘mRNA vaccine’ and the traditional Dead/inactivated pathogen vaccine.




The most popular mRNA vaccine currently available is the Pfizer-BioNTech vaccine. Covid-19 mRNA vaccines are delivered in the upper arm muscle. Once the genetic information (mRNA) has been received by immune cells it stimulates the production of a spike protein specific to the SARS - COV 2 virus. The spike protein is then released into the bloodstream, provoking an immune response. Considering that the fastest vaccine made in human history until now was the measles, mumps and rubella vaccine (MMR) which took four years to develop; it is natural to have some apprehension over the safety and efficacy of this vaccine. Under normal circumstances, making a vaccine takes 10-15 years to develop, due to the complexity of the vaccination development process...


Not to mention, vaccine research carries an immense cost.

In 2018 a study published by The Lancet Global Health estimated the cost of early vaccine development and initial clinical safety trials range from 31 million - 68 million US dollars. In a greatly accelerated timeline of the Covid - 19 pandemic, the cost would be much greater. However, the European Commission has pledged 8 billion US dollars to the development of a Covid - 19 vaccine. Additionally, due to the state of emergency a large amount of lengthy paperwork was eliminated from the process, hence the speediness of it’s production.

Nevertheless, the Covid vaccine, like all others, has had to pass rigorous guidelines of clinical testing.


Vaccine clinical trials are separated into 4 phases;



Phase 1 - the preclinical phase where it is evaluated how the vaccine should work- ensuring that the vaccine delivers the intended results without having to risk human lives as this is initially tested on tissue cultures and animals.

Phase 2 - where the safety and the effective dosage of the vaccine are determined. Although a vaccine is safe if administered in the incorrect dosage, it could potentially pose some health concerns, thus this phase of vaccination is heavily monitored.

Phase 3 - where the effectiveness of the vaccine is determined. Here, percentages can be produced about how effective the vaccine is and/or the likelihood of long-term immunity in order to advise the general public about factual effects of the vaccine.

Phase 4 - regulatory approval and licensing of the vaccine. A considerable portion of vaccine production timeline is in administrative work (licensing, how much the vaccine will cost, which countries require the largest shipments, etc), therefore due to the state of emergency this phase was primarily eliminated, without jeopardizing the safety of the vaccine production.


In times like these, maintaining a positive mindset is hard, however, we all must persevere and play our role in limiting the spread of the virus for each other, our friends and family.