COVID-19 protein subunit vaccines

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About COVID-19 protein subunit vaccines

Many vaccines are being studied to see if they will prevent COVID-19, and Health Canada is prioritizing reviews of all COVID-19 vaccine submissions.

Many types of vaccines use a weakened or inactivated virus or a part of a virus to trigger an immune response inside our body. Protein subunit vaccines contain harmless and purified pieces (proteins) of the virus, which have been specifically selected for their ability to trigger immunity.

Protein subunit vaccines are already used for other diseases. An example of an existing protein subunit vaccine is the one for hepatitis B.

Subunit vaccines cannot cause COVID 19 because they only contain small purified pieces of proteins and not the virus.

Like all vaccines, people who are vaccinated gain protection without ever having to risk the serious consequences of getting sick from being exposed to the virus.

How COVID-19 protein subunit vaccines work

To make the vaccine, a small piece of the virus's genetic code is inserted into another cell (it could be a bacterial, yeast, mammalian or insect cell). The code contains instructions for this cell to start building the virus protein. In this case, it's the Covid-19 'spike' protein, which is known to stimulate immune cells.

The cells then act like factories, building large quantities of the protein. The protein is extracted, purified and used as the active ingredient in the vaccine. Some protein subunit vaccines have adjuvants. An adjuvant is a substance that helps make a stronger and longer-lasting immune response. They have been used safely for decades in a number of vaccines.

Once vaccinated, our immune system recognizes that the proteins don't belong in the body and begins making T-lymphocytes and antibodies. If we're ever infected in the future, memory cells will recognize and fight the virus.

How safe are COVID-19 protein subunit vaccines

The protein pieces in the vaccine are incapable of causing disease and the manufacturing technology is well established. Like all vaccines authorized for use in Canada, COVID-19 protein subunit vaccines will be held to the same high safety, effectiveness and quality standards. Only protein subunit vaccines that meet those standards will be approved.

Once a COVID-19 protein subunit vaccine has been authorized for use in Canada, we will be monitoring its safety and effectiveness (how well it works) 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 are required to 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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