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How COVID-19 vaccines work

Vaccines work by teaching your body’s immune system to remember and recognize a virus. Your body can then defend you if you are exposed in the future.

mRNA vaccines

The Pfizer and Moderna vaccines are mRNA vaccines. These vaccines teach your body to make a piece of a protein from the COVID-19 virus using instructions from the virus, called mRNA.

The instructions tell cells in your body how to make part of a harmless protein from the virus. Once the cells make the protein, the instructions are broken down. The cells display the pieces of protein they’ve created on the outside of your cell and your body recognizes that protein as foreign and develops an immune response. This response will recognize and fight the virus that causes COVID-19 if you are exposed later on. mRNA vaccines do not change or affect your own DNA.


Viral vector-based vaccines

AstraZeneca, COVISHIELD and Janssen (owned by Johnson & Johnson) vaccines are a type of vaccine called a viral vector vaccine.

These vaccines introduce instructions from the virus that causes COVID-19 using a non-COVID-19 virus that has been modified so to be inactive and harmless. This is known as a vector. The vector only carries the instructions to make a specific protein from the COVID-19 virus. Similar to the mRNA virus, once the body creates that protein, it produces an immune response which will recognize and fight future infections.

Learn more from ImmunizeBC on How Vaccines Work.  https://immunizebc.ca/how-do-vaccines-work


Currently all pharmacies in BC that are providing COVID Vaccines are only administering the AstraZeneca/COVIDSHIELD vaccine.

Questions and Concerns About AstraZeneca/COVIDSHIELD Vaccine and Safety visit the following:




Health Canada https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/astrazeneca.html