The Pfizer-BioNTech COVID-19 mRNA vaccine (Tozinameran or BNT162b2) is used to prevent COVID-19. This disease is caused by severe acute respiratory syndrome coronavirus 2 (SARSCoV-2).

The vaccine is approved for people who are 16 years of age and older. Its safety and effectiveness in people younger than 16 years of age have not yet been established.

The Pfizer-BioNTech COVID-19 vaccine is manufactured by Pfizer Canada ULC and BioNTech Manufacturing GmbH. Health Canada authorized this vaccine with conditions on December 9, 2020, under the Interim Order Respecting the Importation, Sale and Advertising of Drugs for Use in Relation to COVID-19.

HOW IT WORKS

mRNA vaccines teach our cells how to make a protein that will trigger an immune response without using the live virus that causes COVID-19. Once triggered, our body then makes antibodies. These antibodies help us fight the infection if the real virus does enter our body in the future.

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

When a person is given the vaccine, their cells will read the genetic instructions like a recipe and produce the spike protein. After the protein piece is made, the cell breaks down the instructions and gets rid of them.

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.

HOW IT’S GIVEN

The vaccine is given by an injection (0.3 mL) into the muscle of the arm. For the vaccine to work best, you need to get 2 doses: a single dose and then a second dose 21 days later.

Based on studies in about 44,000 participants, the Pfizer-BioNTech COVID-19 vaccine was 95% effective in preventing COVID-19 beginning 1 week after the second dose. This means that people may not be fully protected against COVID-19 until at least 7 days after the second dose.

WHAT WILL I FEEL AFTER TAKING THE VACCINE?

Pediatric immunologist Dr. Zainab Abdurrahman explains that vaccines include little bits of a pathogen that trick your body into thinking it is getting infected. That generates an immune response your body will remember if it ever encounters the actual virus. As a result, your body will go through the natural steps of fighting an infection and so you may feel symptoms of illness including fever, localized pain and swelling at the injection site, and general unwellness.

“You can expect to feel similar to how people feel with the influenza vaccine, similar to how you might feel with any of the other vaccines you get,” says Abdurrahman. “These are actually just signs of your immune system working.”

POSSIBLE SIDE EFFECTS

In general, the side effects observed during the clinical trials are similar to what you might have with other vaccines. The side effects that followed vaccine administration in clinical trials were mild or moderate. They included things like pain at the site of injection, body chills, feeling tired and feeling feverish. These are common side effects of vaccines and do not pose a risk to health.

As with all vaccines, there’s a chance that there will be a serious side effect, but these are rare. A serious side effect might be something like an allergic reaction. Speak with your health professional about any serious allergies or other health conditions you may have before you receive this vaccine.

Health Canada has conducted a rigorous scientific review of the available medical evidence to assess the safety of the Pfizer-BioNTech COVID-19 vaccine. No major safety concerns have been identified in the data that we reviewed.

VACCINE SAFETY AFTER AUTHORIZATION

As for all medicines, Health Canada will continue to monitor the safety of the Pfizer-BioNTech COVID-19 vaccine in Canada closely. Along with the Public Health Agency of Canada and working in close collaboration with the provinces and territories and the manufacturer, we will monitor for any adverse events that may develop after immunization.

Once the product is on the market, the manufacturer (Pfizer Canada ULC and BioNTech Manufacturing GmbH) is legally required to submit reports of adverse events to Health Canada.

Health Canada will continue to review all the available safety data as it becomes available. We will take appropriate action, if required, to protect the health and safety of Canadians.