Vaccines & Safety

The Pfizer-BioNTech COVID-19 vaccine uses a method called messenger RNA (mRNA) technology. The mRNA in the vaccine tells the body’s cells to make "spike proteins," similar to what is found on the COVID-19 virus. The immune system responds to the spike proteins by making antibodies. These new antibodies will break down the spike proteins and get rid of them. The new antibodies will protect against COVID-19 infection in the future. The mRNA is broken down by the body shortly after injection and cannot affect the body’s DNA. mRNA vaccines are not live vaccines and cannot cause infection.

Two doses of the vaccine are required for full protection, given up to 16 weeks apart. It can be given to people 12 years of age and older, including seniors. At this time, there is no information on the long-term protection with this vaccine. In trials, the vaccine was 95% effective at preventing symptoms of the COVID-19 virus.

There is a small chance that you may still get COVID-19 after being vaccinated. It is important to continue to follow public health measures such as physical distancing, wearing a mask, and staying home if you are sick. Health care workers and other staff must still wear personal protective equipment (PPE) even after they have been vaccinated.

Some people may experience side effects from the vaccine, but they will likely be moderate and resolve after a few days. Some of the symptoms are part of the body’s response to developing immunity to a virus.

Common side effects that have been reported in clinical trials for this vaccine include:

In rare cases, serious allergic reactions (anaphylaxis) can occur. Allergic reactions can be treated and are usually temporary. Seek medical attention if you have trouble breathing, have hives or swelling of the mouth and throat or a high fever (over 40 degrees C or 104 degrees F). Vaccine side effects will continue to be monitored as people receive the vaccine. If you get a reaction to the vaccine, contact your health care provider who will report the side effect directly to public health. Public health will keep track of the reported side effects to make sure the vaccine continues to be safe.

The Pfizer-BioNTech COVID-19 vaccine may be offered to individuals over the age of 12 who do not have contraindications.

Do not get the Pfizer-BioNTech vaccine if you:

• Have a fever, are sick with COVID-19 symptoms, currently have COVID-19 or have been instructed to self-isolate.
• Have received any vaccine in the past 14 days.
• Have an allergy to an ingredient in the vaccine or have had a previous severe reaction to this vaccine.
  • Visit Health Canada’s vaccine webpages for a list of vaccine ingredients:
    • Health Canada's webpage for Pfizer-BioNTech vaccine ingredients (external link)
    • Health Canada's webpage for Moderna vaccine ingredients (external link)
    • Health Canada's webpage for AstraZeneca vaccine ingredients (external link)
    • Health Canada's webpage for Janssen vaccine ingredients (external link)

Talk to your health care provider before getting the Pfizer vaccine if you:

• Have an autoimmune condition or immunodeficiency condition and are receiving any of the following treatments:
  • stem cell therapy
  • CAR-T therapy
  • chemotherapy
  • immune checkpoint inhibitors
  • monoclonal antibodies (e.g., rituximab) and other targeted agents (e.g., CD4/6 inhibitors, PARP inhibitors etc.)

You can receive the Pfizer vaccine but should consider speaking with your health care provider if you:

• have an autoimmune condition or immunodeficiency condition but are not receiving any of the above treatments
• have a history of allergic reactions not related to the mRNA vaccine
• are pregnant or breastfeeding

The Moderna COVID-19 vaccine uses a method called messenger RNA (mRNA) technology. The mRNA in the vaccine tells the body’s cells to make "spike proteins," similar to what is found on the COVID-19 virus. The immune system responds to the spike proteins by making antibodies. These new antibodies will break down the spike proteins and get rid of them. The new antibodies will protect against COVID-19 infection in the future. The mRNA is broken down by the body shortly after injection and cannot affect the body’s DNA. mRNA vaccines are not live vaccines and cannot cause infection.

Two doses of the vaccine are required for full protection, given up to 16 weeks apart. It can be given to people 18 years of age and older, including seniors. At this time, there is no information on the long-term protection with this vaccine. In trials, the vaccine was 95% effective at preventing symptoms of the COVID-19 virus..

There is a small chance that you may still get COVID-19 after being vaccinated. It is important to continue to follow public health measures such as physical distancing, wearing a mask, and staying home if you are sick. Health care workers and other staff must still wear personal protective equipment (PPE) even after they have been vaccinated.

Health Canada (external link) reported that side effects that followed administration of the Moderna vaccine were mild or moderate and are common of many vaccines, including:

• pain at the site of injection
• body chills
• feeling tired
• feeling feverish

Speak with your health care professional about any serious allergies or health conditions before receiving the Moderna COVID-19 vaccine.

Vaccine side effects will continue to be monitored as people receive the vaccine. If you get a reaction to the vaccine, contact your health care provider who will report the side effect directly to public health. Public health will keep track of the reported side effects to make sure the vaccine continues to be safe.

The Moderna COVID-19 vaccine may be offered to individuals over the age of 18 who do not have contraindications.

Do not get the Moderna vaccine if you:

• Have a fever, are sick with COVID-19 symptoms, currently have COVID-19 or have been instructed to self-isolate.
• Have received any vaccine in the past 14 days.
• Have an allergy to an ingredient in the vaccine or have had a previous severe reaction to this vaccine.
  • Visit Health Canada’s vaccine webpages for a list of vaccine ingredients:
    • Health Canada's webpage for Pfizer-BioNTech vaccine ingredients (external link)
    • Health Canada's webpage for Moderna vaccine ingredients (external link)
    • Health Canada's webpage for AstraZeneca vaccine ingredients (external link)
    • Health Canada's webpage for Janssen vaccine ingredients (external link)

Talk to your health care provider before getting the Moderna vaccine if you:

• Have an autoimmune condition or immunodeficiency condition and are receiving any of the following treatments:
  • stem cell therapy
  • CAR-T therapy
  • chemotherapy
  • immune checkpoint inhibitors
  • monoclonal antibodies (e.g., rituximab) and other targeted agents (e.g., CD4/6 inhibitors, PARP inhibitors etc.)

You can receive the Moderna vaccine but should consider speaking with your health care provider if you:

• have an autoimmune condition or immunodeficiency condition but are not receiving any of the above treatments.
• have a history of allergic reactions not related to the mRNA vaccine
• are pregnant or breastfeeding

The AstraZeneca vaccine is a viral vector vaccine (external link). Unlike the Pfizer-BioNTech and Moderna vaccines which store the instructions to build spike proteins in RNA, the AstraZeneca vaccine uses DNA. The vaccine uses a harmless virus (called an adenovirus) as a delivery system. This is called a viral vector. Once the vaccine containing the viral vector enters the body, the vector virus produces the SARS-CoV-2 spike protein. Just like with the mRNA vaccines, the immune system responds to the spike proteins by making antibodies. These new antibodies will break down the spike proteins and get rid of them. The new antibodies will protect against COVID-19 infection in the future.

DNA is not as fragile as RNA. The viral vector (adenovirus) has a tough protein coat which protects the DNA inside. Therefore, the AstraZeneca vaccine does not need to be kept frozen.

Viral vector technology has been used for over ten years to produce many of the vaccines approved in Canada.

None of the COVID-19 vaccines currently approved by Health Canada use the live virus that causes COVID-19. You cannot get COVID-19 from a vaccine.

Two doses of the vaccine are required, given up to 16 weeks apart. After completing the two-doses, it may take another 14 days to achieve maximum protection against COVID-19. In trials, the vaccine was 81.6% effective at preventing symptoms of the COVID-19 virus. Data from the trials suggests that the vaccine is 100% effective against hospitalization from the COVID-19 disease (22 days after the first dose).

There is a small chance that you may still get COVID-19 after being vaccinated. It is important to continue to follow public health measures such as physical distancing, wearing a mask, and staying home if you are sick. Health care workers and other staff must still wear personal protective equipment (PPE) even after they have been vaccinated.

Common side effects following administration of the AstraZeneca vaccine are typically mild or moderate and are common of many vaccines (external link), including:

• pain at the site of injection
• body chills
• feeling tired
• 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.
 

Ontario pauses use of AstraZeneca

On May 11, the Province announced it would be pausing the rollout and administration of first doses of the AstraZeneca COVID-19 vaccine (external link). The decision was made out of an abundance of caution and due to the increasing reports of the rare blooding clotting condition, known as vaccine-induced immune thrombotic thrombocytopenia (VITT), linked to the AstraZeneca vaccine.

Individuals should seek medical attention if they develop the following symptoms four or more days after receiving the AstraZeneca COVID-19 vaccine:

• shortness of breath
• chest pain
• leg swelling
• persistent abdominal (belly) pain
• neurological symptoms (such as sudden onset of severe or persistent worsening headaches or blurred vision)
• skin bruising or tiny blood spots under the skin beyond the site of the injection

If you experienced rare blood clots with unusual platelets following your first dose of the AstraZeneca COVID-19 vaccine, it is not recommended that you receive a second dose of any version of the AstraZeneca vaccine.

For more information on the safety of the AstraZeneca vaccine, please read Health Canada’s website (external link).

The AstraZeneca COVID-19 vaccine has been approved by Health Canada for individuals over the age of 18 who do not have contraindications.

Do not get the AstraZeneca vaccine if you:

• Have a fever, are sick with COVID-19 symptoms, currently have COVID-19 or have been instructed to self-isolate.
• Have received any vaccine in the past 14 days.
• Have an allergy to an ingredient in the vaccine or have had a previous severe reaction to this vaccine.
  • Visit Health Canada’s vaccine webpages for a list of vaccine ingredients:
    • Health Canada's webpage for Pfizer-BioNTech vaccine ingredients (external link)
    • Health Canada's webpage for Moderna vaccine ingredients (external link)
    • Health Canada's webpage for AstraZeneca vaccine ingredients (external link)
    • Health Canada's webpage for Janssen vaccine ingredients (external link)

Talk to your health care provider before getting the AstraZeneca vaccine if you:

• Have an autoimmune condition or immunodeficiency condition and are receiving any of the following treatments:
  • stem cell therapy
  • CAR-T therapy
  • chemotherapy
  • immune checkpoint inhibitors
  • monoclonal antibodies (e.g., rituximab) and other targeted agents (e.g., CD4/6 inhibitors, PARP inhibitors etc.)

You can receive the AstraZeneca vaccine but should consider speaking with your health care provider if you:

• have an autoimmune condition or immunodeficiency condition but are not receiving any of the above treatments.
• have a history of allergic reactions, or;
• are pregnant or breastfeeding

Additional information will be posted as it is released from Health Canada.

The Janssen vaccine is a viral vector vaccine (external link). Unlike the Pfizer-BioNTech and Moderna vaccines which store the instructions to build spike proteins in RNA, the Janssen vaccine uses DNA. The vaccine uses a harmless virus (called an adenovirus) as a delivery system. This is called a viral vector. Once the vaccine containing the viral vector enters the body, the vector virus produces the SARS-CoV-2 spike protein. Just like with the mRNA vaccines, the immune system responds to the spike proteins by making antibodies. These new antibodies will break down the spike proteins and get rid of them. The new antibodies will protect against COVID-19 infection in the future.

DNA is not as fragile as RNA. The viral vector (adenovirus) has a tough protein coat which protects the DNA inside. Therefore, the Janssen vaccine does not need to be kept frozen.

Viral vector technology has been used for over ten years to produce many of the vaccines approved in Canada.

None of the COVID-19 vaccines currently approved by Health Canada use the live virus that causes COVID-19. You cannot get COVID-19 from a vaccine.

A single dose of the vaccine is required. It can be given to people over 18 years of age. In trials, the vaccine was 66% effective at preventing moderate to severe COVID-19.

There is a small chance that you may still get COVID-19 after being vaccinated. It is important to continue to follow public health measures such as physical distancing, wearing a mask, and staying home if you are sick. Health care workers and other staff must still wear personal protective equipment (PPE) even after they have been vaccinated.

Common side effects following administration of the Janssen vaccine are typically mild or moderate and are common of many vaccines, including:

• pain at the site of injection
• body chills
• feeling tired
• 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.

Safety Concerns: Vaccine-Induced Thrombotic Thrombocytopenia (VITT)

Individuals should seek medical attention if they develop the following symptoms four or more days after receiving the Janssen (COVISHIELD) COVID-19 vaccine:

• shortness of breath
• chest pain
• leg swelling
• persistent abdominal (belly) pain
• neurological symptoms (such as sudden onset of severe or persistent worsening headaches or blurred vision)
• skin bruising or tiny blood spots under the skin beyond the site of the injection

For more information on the safety of the Janssen (COVISHIELD) vaccine, please read Health Canada’s website (external link).

The Janssen COVID-19 vaccine is approved for use in people 18 years of age and over.

Additional information will be posted as it is released from Health Canada.