With over 150 million COVID-19 vaccine doses given worldwide, we take a deeper look into the different types of vaccines being used and developed, and how each one works.
Viral Vector
This type of vaccine involves taking a harmless virus and altering part of its genetic code to give it a similar characteristic to the COVID-19 virus, such as creating protein ‘spikes’ on its surface. This triggers an immune response, which prepares the immune system to be able to fight the real virus later.
The first vaccine of this kind to be approved was the Oxford/AstraZeneca vaccine, while many others are currently in late-stage research (such as Johnson & Johnson). This is also the same technology used in the Ebola vaccine.
RNA
To produce this type of vaccine, scientists create a synthetic version of the COVID-19 virus’ messenger RNA (molecules responsible for putting DNA instructions into action). Our bodies read this genetic code and start building specific proteins, such as COVID-19’s ‘spike’ protein, which our immune system responds to and then learns how to protect against.
There are currently two RNA vaccines approved for use, Pfizer-BioNTech and Moderna, and both have reported very high levels of efficacy (around 95%).
‘Whole’ Virus
These vaccines can be either inactivated (a version of the COVID-19 virus that has been killed) or attenuated (a weakened version of the virus that does not cause any illness). In both instances, the immune system triggers a response and builds immune memory so that it can effectively fight COVID-19 in future.
There are a variety of ‘whole’ virus vaccines in development, including Sinovac, Sinopharm and Codagenix.
Protein
This type of vaccine involves inserting a small piece of the COVID-19 genetic code into another cell, which is programmed to start building specific virus proteins, such as the COVID-19 ‘spike’ protein. Large quantities of these proteins can then be injected into the body to allow the immune system to fight and recognise this type of protein, thereby protecting against future infection.
Clinical trials are currently underway using this technology, including the Novovax and Sanofi-GSK vaccines.
