The Coronavirus vaccines: explained

Updated: Apr 2

By Kat McGregor


Coronavirus (Covid-19) was first reported just over a year ago, and is already responsible for more than 2 million deaths globally. Thanks to scientists’ incredible work, soon enough, we should see the descent of case numbers through the roll-out of vaccines across the UK and worldwide.


There are three brands of vaccines in the UK approved to protect against Covid-19: Pfizer/BioNTech, Oxford/AstraZeneca and Moderna.


But what is a vaccine?


Vaccines are simple, safe injections that protect against pathogens such as viruses and bacteria. They train your body’s immune system into producing antibodies – protective proteins that can recognise and latch onto specific proteins (antigens) of the pathogen to remove them from the body.


So why is there more than one vaccine in the UK?


When scientists are developing vaccines, there is a long process of checks to ensure they are safe for the public. These tests are so intensive that only 7 out of every 100 vaccines developed will be deemed safe.


Through the rapid development of technology and an increase in research funding, three of these vaccines have passed all necessary checks. They have been deemed safe for use by the government drug agency, the MHRA, an unprecedentedly fast turnaround.


The BBC have made a handy table (below) showing information on the types of vaccines available.

Source: BBC.co.uk


What is the difference between each vaccine?

Source: who.int


There are three main approaches to vaccine development: using the whole micro-organism, parts of the micro-organism, or the genetic material (the instructions for making specific proteins).


The whole micro-organism approach

These are some of the oldest approaches to vaccines and involve using a whole (weakened or dead) version of the pathogen to activate an immune response in the body.


Live-attenuated vaccine

The injection of a weakened version (genetically modified by nature or scientist) of a living pathogen to offer long-term protection.


Inactivated vaccine

Whole bacteria or viruses that have been killed, or inactivated, so they cannot replicate. These vaccines do not cause any disease but initiate an immune response as the “shape” of the proteins remain to be identified by antibodies as foreign.


Viral vectored vaccines

The method used by Oxford/AstraZeneca. A harmless virus (the vector) delivers some genetic code for pathogenic antigens (the proteins the immune system can recognise).Researchers remove the vector’s ability to replicate so that the vaccine cannot cause disease.


The subunit approach

The most common vaccine approach used in the UK. This approach doesn’t contain a whole pathogen, but specific parts (subunits) of a virus or bacterium that the immune system needs to recognise it.


The genetic material approach


Nucleic acids: how proteins are made

DNA and RNA are nucleic acids – the instructions used to make proteins in all cells. In all cells, DNA is the first part of the instruction, which then acts as a template to produce mRNA (messenger RNA). mRNA is a blueprint for protein production.


The method used by Pfizer/BioNTech and Moderna.

These approaches are called nucleic acid vaccines. Instead of delivering whole or parts of a pathogen, they deliver parts of the antigens’ genetic instructions to cells in the body.


The human immune cells then make the antigen themselves, which can then be recognised and stimulate an immune response.