COVID-19 Vaccine

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, which will protect against COVID-19 infection in the future. These new antibodies will break down the COVID-19 spike proteins and get rid of them. 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. The vaccine is given by injection into the muscle of the arm. 

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:

Very common ≥10% (more than 1 in 10 doses)

• Pain at the injection site
• Headache
• Feeling tired
• Muscle or joint pain
• Fever or chills

Common 1%-10% (1 in 100 to 1 in 10 doses)

• Redness and swelling at the injection site

Uncommon 1% (1 in 100 doses)

• Enlarged lymph nodes

In rare cases, serious allergic reactions (anaphylaxis) can occur. Allergic reactions can be treated and are usually temporary. 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. 

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. 

• Rare cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) following vaccination with COVID-19 mRNA vaccines have been reported in Canada and internationally.

• Symptoms of myocarditis/pericarditis can include shortness of breath, chest pain, or the feeling of a rapid or abnormal heart rhythm. Symptoms can be accompanied by abnormal test results (e.g., electrocardiogram, serum troponins, echocardiogram).

• International cases are consistently reported to have occurred:
  • More often after the second dose
  • Usually within a week after vaccination
  • More often in adolescents and young adults (12 to 30 years of age)
  • More often in males than females.
• The reporting rate for the Moderna vaccine was 6.6 per million doses administered following first dose and 28.2 per million doses administered following second dose, for all age groups and genders combined.
• Most cases appear to be mild and respond well to conservative treatment (e.g. non-steroidal anti-inflammatory drugs) and rest.
• COVID-19 vaccines continue to be recommended and are highly effective at preventing symptomatic infection and severe outcomes from COVID-19 disease, which is also associated with a risk of myocarditis. 

The vaccine is approved for people who are 12 years of age and older who do not have any contraindications.

Do not get a COVID-19 vaccine if you:

• Have a fever, are sick with COVID-19 symptoms, currently have COVID-19 or have been instructed to self-isolate.
• Have an allergy to an ingredient in the vaccine or have had a previous severe reaction to this vaccine.

Visit Health Canada’s vaccine webpage (Pfizer-BioNTech) for a list of vaccine ingredients.

Learn more about COVID-19 Vaccines for Children.

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, which will protect against COVID-19 infection in the future. These new antibodies will break down the COVID-19 spike proteins and get rid of them. 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. The vaccine is given by injection into the muscle of the arm. 

Health Canada 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

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. 

• Rare cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) following vaccination with COVID-19 mRNA vaccines have been reported in Canada and internationally.

• Symptoms of myocarditis/pericarditis can include shortness of breath, chest pain, or the feeling of a rapid or abnormal heart rhythm. Symptoms can be accompanied by abnormal test results (e.g., electrocardiogram, serum troponins, echocardiogram).

• International cases are consistently reported to have occurred:
  • More often after the second dose
  • Usually within a week after vaccination
  • More often in adolescents and young adults (12 to 30 years of age)
  • More often in males than females.
• The reporting rate for the Moderna vaccine was 6.6 per million doses administered following first dose and 28.2 per million doses administered following second dose, for all age groups and genders combined.
• Most cases appear to be mild and respond well to conservative treatment (e.g. non-steroidal anti-inflammatory drugs) and rest.
• COVID-19 vaccines continue to be recommended and are highly effective at preventing symptomatic infection and severe outcomes from COVID-19 disease, which is also associated with a risk of myocarditis. 

Effective September 29, 2021, Pfizer-BioNTech is recommended for 12-24 year olds due to an observed increase in Ontario of pericarditis/myocarditis following vaccination with Moderna compared to Pfizer in the 18 to 24 year old age group, particularly among males.

The vaccine is approved by Health Canada for people who are 12 years of age and older who do not have any contraindications.

In Ontario, the Ministry of Health recommends Moderna for people who are 25 years of age and older and who do not have any contraindications. Pfizer-BioNTech is recommended for 12-24 year olds. This recommendation is due to an observed increase in Ontario of pericarditis/myocarditis following vaccination with Moderna compared to Pfizer in the 18 to 24 year old age group, particularly among males.

Should individuals aged 18 to 24-year old wish to receive Moderna they can continue to do so with informed consent.

Do not get a COVID-19 vaccine if you:

• Have a fever, are sick with COVID-19 symptoms, currently have COVID-19 or have been instructed to self-isolate.
• Have an allergy to an ingredient in the vaccine or have had a previous severe reaction to this vaccine.

Visit Health Canada’s vaccine webpage (Moderna) for a list of vaccine ingredients. 

This 50 mcg formulation contains equal parts (25 mcg each) of mRNA encoding for the original SARS-CoV-2 virus and the Omicron BA.1 variant. When administered as a second booster dose, Moderna Spikevax Bivalent (50 mcg) elicited higher neutralizing antibody responses against the original strain, Omicron BA.1 and Omicron BA.4 and BA.5 among individuals with and without prior infection when compared to a second booster dose of Moderna Spikevax original (50 mcg). 

This effect was consistent across age groups studied, in individuals 18-65 years of age and individuals >65 years of age.

For more information please visit the National Advisory Committee on Immunization and Government of Canada Recommendations 

The frequency of adverse events following Moderna Spikevax Bivalent (50 mcg) given as a second booster dose was similar or lower compared to that of a first booster dose of Moderna Spikevax original (50 mcg), and of the second dose of the Moderna Spikevax original primary series (100 mcg). There were no vaccine-related cases of myocarditis, pericarditis or deaths reported during the study period.

Available surveillance data to date from Canada and international jurisdictions indicate that the risk of myocarditis and/or pericarditis following a first booster dose of an original mRNA COVID-19 vaccine using manufacturer-authorized booster dosage appears to be lower than the risk following the second dose of the primary series. In addition, preliminary safety data indicate that the risk of myocarditis and/or pericarditis associated with a second booster dose of an original mRNA COVID-19 vaccine is lower than the risk following the second dose of the primary series.

This vaccine has been approved for the following groups for as long as it's been six months since their last dose:

• Residents of congregate living settings
• Individuals 70 years of age and older
• Individuals who are pregnant and are 18+ years old
• Individuals aged 12 and older who are immunocompromised
• First Nations, Métis and Inuit people and members of their household who are 18 and older
• Health care workers who provide direct care, including first responders 18+ years old

The National Advisory Committee on Immunization (NACI) recommends that if a risk assessment with a health care provider deems that the benefits outweigh the potential risks, and if informed consent includes discussion about the absence of evidence on the use of COVID-19 vaccine then a complete series of COVID-19 vaccine may be offered to individuals who are pregnant or breastfeeding/chestfeeding. 

The National Advisory Committee on Immunization (NACI) recommends that if a risk assessment with a health care provider deems that the benefits outweigh the potential risks, and if informed consent includes discussion about the absence of evidence on the use of COVID-19 vaccine then a complete series of COVID-19 vaccine may be offered to individuals who are immunosuppressed due to disease or treatment or suffering from an autoimmune disorder.

Individuals who have had a severe allergic reaction or a suspected allergic reaction within 4 hours of receiving a previous dose of COVID-19 vaccine should be referred to an allergist/immunologist for consultation and to discuss options for future vaccinations.

If this applies to you, you will not be able to receive COVID-19 vaccination at a mass immunization clinic. Please contact 519-575-4400 to cancel your scheduled appointment.

I have had an allergic reaction within 4 hours and/or anaphylaxis that occurred with a different vaccine or injectable medication that does not contain a component of COVID-19 vaccine.

Please contact your treating health care provider to have a discussion about COVID-19 vaccination. Your health care provider may refer you to an allergist/immunologist for consultation. After this consultation you may decide:

• To receive the vaccine. At your appointment, you will be asked for documentation from your health care provider indicating that it is safe to receive the vaccine and if any specific conditions apply. You will be asked to wait 30 minutes after vaccination to monitor for adverse effects
• Not to receive the vaccine. Please contact 519-575-4400 to cancel your scheduled appointment.

I have had an allergic reaction to a food, drug, venom, latex or other allergen not related to COVID-19 vaccine OR I have allergic rhinitis (e.g. seasonal allergies), asthma or eczema.

You may receive COVID-19 vaccination if your condition/treatment is under control and you are able to receive injections or have blood work. 

After immunization, you will be asked to apply firm pressure to the injection site for 5-10 minutes.

If you are not able to receive injections or have blood work, please contact 519-575-4400 to cancel your scheduled appointment and consult with your health care provider about options for vaccination.