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How do the new vaccines work?

In a nutshell, vaccines train our immune system so it is ready to respond if we are ever exposed to the virus that causes COVID-19. You can’t get the virus from these vaccines.

COVID-19 viruses have spikes on the surface, called spike proteins, which they use to attach and enter human cells. These spikes allow the virus to infect you. The vaccines target these spike proteins, helping your immune system to recognize them in the future to prevent COVID-19 infection and illness. 

All approved vaccines are highly effective at preventing severe illness, hospitalization and death.

Pfizer and Moderna mRNA Vaccines

Two vaccines approved for use in Canada, from Pfizer (Comirnaty) and Moderna (Spikevax), use messenger RNA, or mRNA, technology. 

These vaccines train our body to make a harmless piece of what is called the spike protein found on the surface of the virus that causes COVID-19. This triggers an immune response, something our body will remember if we are exposed to COVID-19 in the future. What is left from the vaccine is quickly broken down and expelled from our body.

While this is a new vaccine, it is not new technology. The messenger RNA response has been used for other vaccines and medical treatments, including for cancer. 

The mRNA vaccines do not contain the live virus that causes COVID-19, and they cannot affect our DNA in any way. 

Oxford-AstraZeneca Viral Vector Vaccine

Unlike many other vaccines, non-replicating viral vector vaccines use a harmless cold virus to deliver the genetic code from the spike on the surface of the COVID-19 virus. This trains our immune system to react in the future.

This technique has been used in the past, most notably in a vaccine approved for Ebola. This type of vaccine is more rugged than mRNA vaccines, so they don’t need to be frozen.

Find out more about how these vaccines work:

About the Moderna COVID-19 Vaccine (Health Canada)

About the Pfizer-BioNTech COVID-19 Vaccine (Health Canada)     

About the AstraZeneca COVID-19 Vaccine (Health Canada)

About the Johnson & Johnson (Janssen) Vaccine (Health Canada)

Understanding mRNA COVID-19 Vaccines (CDC in U.S.)

Understanding Viral Vector Vaccines (CDC in U.S.)

How do Vaccines Work? (World Health Organization)

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