The start of the pandemic activated many researchers and pharmaceutical companies to start developing vaccines against the virus SARS-CoV-2. Multiple different techniques are used for these vaccines. Some have obtained approval to be used in people, while others are still in various stages of development.
Below we provide an overview of the main types of vaccines available or in development.
RNA vaccines
These vaccines make use of a piece of messenger RNA (mRNA) that serves as an instruction manual for your cells to produce a protein from the virus. For instance, the Spike protein, which is part of the virus’s outer layer, is used. Cells that come into contact with the vaccine will produce the protein. This protein is then shown to the immune cells, who develop an immune response against it.
Read more about how mRNA vaccines work.
Examples: Pfizer-BioNTech, Moderna
Vector-based vaccines
These types of vaccines use a harmless virus to humans. This is a virus that does not cause disease and cannot replicate in your body. In this case, most often, an adenovirus is used. The virus serves as the delivery system to provide your cells with instructions to produce the Spike protein of the SARS-CoV-2 virus. This protein is then shown to your immune cells, who develop an immune reaction against it.
Read more about how the immune response works.
Examples: AstraZeneca-Oxford, Johnson & Johnson, Gamaleya (Sputnik), CanSino
Protein-based vaccines
These types of vaccines use a protein, in this case, the Spike protein. A recombinant version of the spike protein is used; this means that the protein is produced in a laboratory. So, for this vaccine, your cells do not have to create the protein itself.
In the lab, the recombinant spike protein is mixed with nanoparticles that bind the protein to it. These nanoparticles with the protein are injected as the vaccine. Another ingredient of these vaccines is called an adjuvant. This is a compound that stimulates and gathers the immune cells to the location where you are injected with the nanoparticles. The immune cells will then be exposed to the Spike protein and be trained to recognize it in the future.
Read more about how the immune response works.
Examples: Novavax, Vector Institute
Inactivated virus vaccines
This type of vaccine uses the SARS-CoV-2 virus. In the lab, this virus is treated with a chemical that changes the virus and inactivates it. This means that the virus cannot longer replicate, so it cannot spread in the body and cause disease. This inactivated virus is mixed with an adjuvant to form the vaccine that is injected. The adjuvant stimulates the immune cells to come into action against the virus. This way, the immune response is trained to detect the virus if you would encounter it later in life.
It is important to note that because the virus is inactivated, it cannot give you COVID-19.
Examples: Sinopharm, Sinovac, Bharat Biotech
These are the main subtypes of vaccines currently in use and development. We will keep you updated about new developments in this area of research.
Further Reading:
NY Times: Coronavirus Vaccine Tracker
RAPS: COVID-19 vaccine tracker
Contributed by: Text: Maartje Wouters