COVID-19 mRNA vaccines

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About COVID-19 mRNA vaccines

Two of the vaccines approved for use in Canada are messenger RNA vaccines (called mRNA vaccines):

mRNA vaccines are a new type of vaccine. They don't use live virus to trigger an immune response. Instead, they teach your cells how to make a protein that will trigger an immune response. Once triggered, your body makes antibodies. These antibodies help you fight the infection if the real virus does enter your body in the future.

Researchers have been studying and working with mRNA vaccines for quite some time. For example, they've been studied for use in flu, Zika, rabies and cytomegalovirus (CMV). Researchers have also used mRNA to trigger the immune system to target certain cancer cells.

mRNA vaccines can be developed faster than traditional methods because they're made in a lab using materials that are easily available. Once developed, large-scale clinical trials are carried out to show that the vaccines are safe and effective.

mRNA vaccines can also be adapted relatively quickly to protect against new variants of a virus. This approach builds on the original clinical trials and evaluates the improved immune response with the new variant.

As with all vaccines, you gain protection from an mRNA vaccine without having to risk the serious consequences of getting sick from the virus.

You can't get COVID-19 from the vaccine itself.

How COVID-19 mRNA vaccines work

Messenger ribonucleic acid (mRNA) is a molecule that provides cells with instructions for making proteins. mRNA vaccines contain the instructions for making the SARS-CoV-2 spike protein. This protein is found on the surface of the virus that causes COVID-19.

The mRNA molecule is essentially a recipe, telling the cells of the body how to make the spike protein.

COVID-19 mRNA vaccines are given by injection, usually into the muscle of the upper arm.

After the protein piece is made, the cell breaks down the instructions and gets rid of them. The mRNA never enters the central part (nucleus) of the cell, which is where our DNA (genetic material) is found. Your DNA can't be altered by mRNA vaccines.

The cell then displays the protein piece on its surface. Our immune system recognizes that the protein doesn't belong there and begins building an immune response and making antibodies.

Bivalent COVID-19 mRNA vaccines

Scientists and vaccine manufacturers are updating COVID-19 vaccines by adding other ingredients which specifically target the circulating virus strains. A “bivalent” vaccine targets two coronavirus strains. This helps to create a broader immune response and improve the strength and duration of protection against circulating variants.

mRNA vaccine safety

COVID-19 mRNA vaccines are held to the same high standards for safety, effectiveness and quality as all vaccines authorized for use in Canada. Only vaccines that meet those standards can be approved.

Once approved, we continue to monitor all vaccines for safety and effectiveness in people.

We have a strong monitoring system for drug safety in Canada. Anyone who witnesses or experiences a side effect to a vaccine is strongly encouraged to report it to their health care provider.

Health care providers must report adverse events following immunization to their local public health authority. The public health authority then reports them to the Public Health Agency of Canada.

For more information on drug safety, see safety after authorization for vaccines and treatments for COVID-19.

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