Viral vector-based vaccines for COVID-19

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About COVID-19 viral vector-based vaccines

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

Most COVID-19 vaccines being developed help the body develop an immune response against what's called the spike protein on the outside of the coronavirus. Just like with a natural infection, when the immune cells in the body are exposed to parts of the virus in a vaccine, antibodies are developed and immune cells are primed to respond to prevent infection.

Some of the vaccine candidates that are most advanced in development are viral vector-based vaccines. These types of vaccines use a harmless virus (in this case, the adenovirus) as a delivery system. The vector virus used is not the virus that causes COVID-19.

Adenoviruses are viruses that cause the common cold. There are many different types, including those that cause colds in humans and those that may infect other species. People have been using these viruses for decades to deliver the instructions for proteins.

Once injected into the body, the virus contained within the vaccine produces the SARS-CoV-2 spike protein. This protein doesn't make you sick. It does its job and then goes away.

Through this process, the body is able to mount a strong immune response against the spike protein without exposing you to the virus that causes COVID-19.

What we know about the safety of viral vector-based vaccines

Viral vector-based technology has been used to develop many vaccines for animals. It's also an emerging technology for use in human vaccines, including an Ebola vaccine, which has been approved by a number of international regulators. There's always a lot of attention paid to safety when a vaccine is developed. Everything we know about how viruses grow and make proteins is strictly controlled when a vaccine is designed.

Like all vaccines authorized for use in Canada, COVID-19 viral vector-based vaccines will be held to the same high safety, effectiveness and quality standards. Only vaccines that meet those standards will be approved.

Once a COVID-19 viral vector-based 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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