Last updated: August 3, 2022 at 10:53 a.m.

It is recommended that everyone age 6 months and older get and stay up to date with their COVID-19 vaccination, including any booster dose(s) when eligible, for the best protection against getting very sick from COVID-19. Even if you recently got COVID-19, getting vaccinated helps to have stronger and longer lasting immunity. See COVID-19: Where to Get Vaccinated to find a vaccine clinic near you.

COVID-19 vaccines teach our immune system to make antibodies that protect us from the COVID-19 virus. Staying up to date with your COVID-19 vaccination, including any booster dose(s) when eligible, will reduce the risk of getting, spreading, and becoming seriously sick with COVID-19. It can also help lower the risk of long COVID. None of the vaccines contain COVID-19 and cannot give you the virus.

The vaccine doses are given using a needle in your upper arm. It takes at least two weeks after getting a vaccine dose to be protected. The Pfizer-BioNTech, Moderna, Novavax, Medicago and AstraZeneca vaccines require two doses to complete a primary series, and one dose for the Janssen vaccine. Boosters are required for the best protection for anyone 12 years of age and older.

The Pfizer-BioNTech and Moderna Spikevax vaccines are ‘messenger RNA’ or ‘mRNA’ vaccines. They use mRNA to give our cells instructions to make antibodies. The mRNA does not change our DNA. mRNA vaccines are interchangeable – take the first vaccine that is available to you, regardless of any previous doses.

Health Canada authorized the following mRNA vaccines in Canada:

  • Pfizer-BioNTech (also known as Pfizer) approved:
    • December 9, 2020 for 16 years and older
    • May 5, 2021 for 12 years and older
    • Pediatric Pfizer in November 2021 for 5 to 11 year olds
  • Moderna Spikevax (also known as Moderna) approved:
    • December 23, 2020 for 16 years and older
    • August 27, 2021 for 12 years and older.
    • March 17, 2022 a half dose for 6 to 11 year olds
    • Pediatric Moderna on July 14, 2022 for 6 months to 5 years old.

Learn more on how the mRNA vaccines work.

Update on Messenger RNA (mRNA) vaccines

Myocarditis and Pericarditis

  • Myocarditis and pericarditis are types of inflammation in different parts of the heart. It can occur after a COVID-19 infection and can be serious.
  • These types of inflammation of the heart can be caused by the body’s response to an infection, injury or complications of an auto-immune disease.

In Canada, there have been rare reports of myocarditis/pericarditis after getting a COVID-19 mRNA vaccine. The situation is being closely monitored. Most people who have gotten myocarditis/pericarditis after vaccination has had a mild illness and symptoms went away without any concerns about long-term complications. A COVID-19 infection can cause a much more serious myocarditis/pericarditis. For this reason, vaccination is still recommended as the benefits outweigh the risks.

In alignment with the National Advisory Committee on Immunization, Ontario’s Ministry of Health issued a preferential recommend the Pfizer-BioNTech vaccine for youth aged 12-29 years old. This is due to an observed increase in Ontario of pericarditis/myocarditis following vaccination with Moderna compared to Pfizer, especially in young adult and teen males. People who are 18-29 years old can still get the Moderna vaccine with informed consent.

Myocarditis/pericarditis is even rarer in children 5 to 11 years of age following the Pediatric Pfizer-BioNTech vaccine. Millions of doses have been given to children around the world showing this vaccine is very safe in children.

The clinical trial for the Pediatric Moderna vaccine showed no cases of myocarditis and pericarditis in children under 5 years of age.

These vaccines continue to be closely monitored. While less common, COVID-19 infections in children can lead to serious complications in children, including in healthy children. For this reason, vaccination is still recommended as the benefits outweigh the risks.

Toronto Public Health closely monitors COVID-19 vaccine safety alongside federal and provincial public health agencies to ensure vaccines continue to be safe.

Potential Side Effects and Seeking Medical Attention

Most side effects of COVID-19 vaccines are mild and last for 1-3 days.

Severe side effects are rare. Get medical attention right away if you develop any of these symptoms after receiving a vaccine:

  • Chest pain/feelings of pressure or tightness
  • Shortness of breath
  • Heart palpitations/irregular heart beat

More Information

The Novavax Nuvaxovid vaccine (also known as Novavax) was authorized for use by Health Canada on February 17, 2022, for adults aged 18+.

The National Advisory Committee on Immunization (NACI) strongly recommends mRNA vaccines (Pfizer-BioNTech, Moderna) for all eligible age groups because they are safer and more effective.

For adults (18+) unable (due to allergy) or unwilling to get an mRNA vaccine, Novavax Nuvaxovid is another option instead of a mRNA vaccine.

Novavax is a ‘protein subunit’ vaccine. It uses small pieces of a protein that look like the spikes on the COVID-19 virus. These proteins teach our immune system to make antibodies that recognize and fight COVID-19.

  • Two doses are required in a primary series. It takes two weeks after vaccination for protection.
  • Novavax can be used to complete a primary series, even if the previous vaccine was a different type (e.g. one dose of another COVID-19 vaccine and one dose of Novavax).
  • A booster dose is recommended for everyone who is eligible, even though Novavax has not been currently authorized as a booster by Health Canada. Novavax can be used as a booster dose even if the primary series used a different type of COVID-19 vaccine.

Some people may have mild to moderate side effects from this vaccine that may last one to three days. Common side effects include redness, pain or swelling at the injection site, mild fever, headache, feeling tired, muscle aches, joint pain, nausea and/or vomiting. Contact your health provider if side effects do not go away after 3 days.

Myocarditis and pericarditis are types of inflammation in different parts of the heart that can occur after getting COVID-19 and be serious. This has rarely occurred after getting Novavax and is being closely monitored. Get medical attention if you develop chest pain, shortness of breath, or racing heartbeat after vaccination.

People with a serious allergy to another COVID-19 vaccine or polyethylene glycol (PEG) can consider getting Novavax.

The Novavax vaccine is available at all City-run clinics through appointment only.

Book your appointment

The AstraZeneca and Janssen vaccines are ‘viral vector’ vaccines. They use a modified cold virus (adenovirus) to give our cells instructions to make antibodies. The cold virus in the vaccine is inactive and will not give you a cold.

The viral vector vaccines approved in Canada are:

  • The AstraZeneca vaccine (also known as Vaxzeria or previously known as COVISHIELD) was authorized for use by Health Canada on February 26, 2021, for adults aged 18+. It is currently not available in Canada.
  • The Janssen vaccine (also known as Johnson & Johnson) was authorized for use by Health Canada on March 5, 2021 for adults aged 18+. Small quantities may be available.

The National Advisory Committee on Immunization (NACI) strongly recommends mRNA vaccines (Pfizer-BioNTech, Moderna) for all eligible age groups because they are safer and more effective.

For adults (18+) unable (due to allergy) or unwilling to get an mRNA vaccine, Novavax Nuvaxovid (a protein subunit vaccine) is another option instead of a mRNA vaccine. The Novavax vaccine can be used even if someone got a viral vector vaccine for their first dose.

Anyone who wants to get a viral vector COVID-19 vaccine (Janssen) should consult a health care provider to help make an informed decision about:

  • Individual risks and very rare reactions found to occur with viral vector vaccines, including:
    • Vaccine-induced immune thrombotic thrombocytopenia (VITT)
    • Capillary leak syndrome (CLS)
    • Guillain-Barré syndrome (GBS)
    • Immune thrombocytopenia (ITP)
    • Venous thromboembolism (VTE)
  • The risk and symptoms of VITT. Should symptoms develop in the first month following vaccination, seek immediate medical care. Symptoms may include:
    • severe and persistent headache; seizures; blurred or double vision; shortness of breath; severe chest, back or abdominal pain; limb swelling, pallor or coldness; unusual bleeding, bruising, pinpoint round spots under the skin beyond the site of vaccination
  • Benefits of vaccination to lower the risk of severe COVID-19 infections (such as getting very sick, being hospitalized and possibly death)
  • Any previous or severe allergic reaction to the mRNA vaccine
  • Any contraindications or concerns in accessing an mRNA vaccine

AstraZeneca/COVIDSHIELD COVID-19 vaccine

Effective May 11, 2021, the Government of Ontario paused the AstraZeneca COVID-19 vaccine until further notice.

Already received a first dose of AstraZeneca/COVISHIELD

If you already got a first dose of the AstraZeneca or COVISHIELD vaccine, it is important to remember that serious side effects are rare. After 28 days of getting the vaccine, the risk of severe side effects has passed. You can finish your vaccine series with a mRNA vaccine. Learn more about how to book your second dose.

Janssen (Johnson & Johnson) COVID-19 vaccine

  • The Janssen single dose vaccine has been approved for people 18 years of age and older. It is not authorized for people younger than 18 years old.
  • A single dose of mRNA vaccine is still preferred over a single dose of the Janssen vaccine.
  • If you have moderate to severe problems with your immune system, it is recommended that you get an mRNA COVID-19 vaccine.

Already received a complete series of a Viral Vector Vaccine

  • People who received a complete vaccine series of a viral vector vaccine (e.g. two doses of AstraZeneca or one dose of Johnson & Johnson), it is recommended to get a booster dose of an mRNA COVID-19 vaccine.
  • This should be given ~six months (≥168 days) after the completion of the primary series

More information

Health Canada approved the Medicago vaccine (also known as Covifenz) on February 24, 2022, for adults 18 to 64 years of age.

The Medicago vaccine is a plant-based vaccine. It uses virus-like particles (VLP) that look like the COVID-19 virus and teach our immune system to make antibodies that recognize and fight COVID-19.

This vaccine is currently not available in Canada.

  • Omicron is a variant of concern (VOC) and has many mutations compared to past variants, such as Delta.
  • Some people may become infected again with COVID-19 after experiencing a previous COVID-19 infection. People who recently had COVID-19 should continue to reduce their risk of getting it again by following public health measures.
  • Staying up-to-date with COVID-19 vaccines, including any booster dose(s) when eligible, lowers the risk of getting, spreading and becoming seriously sick with COVID-19. Vaccination, even after a recent COVID-19 infection, provides even better and longer lasting protection. Find out when to get the vaccine after a recent infection.
  • The current vaccines provide good protection against getting very sick from the variants that have circulated in Ontario.

An AEFI is any time you feel unwell more than what you were told to expect after receiving a vaccine. If you think you are experiencing an AEFI, contact your health care provider and let them know you feel unwell and recently received a vaccine.

AEFIs are reported by your health care provider to Toronto Public Health (TPH), who helps your provider investigate if your illness was caused by the vaccination. TPH reports AEFIs to the Ontario Ministry of Health, Public Health Ontario, and the Public Health Agency of Canada to make sure that vaccines are as safe as possible, even after they are approved. Companies that produce vaccines do not help with investigations of AEFIs, but they are aware of reports for the safety of their products.

The vaccine contains an active ingredient that gives our body instructions to make antibodies. Other vaccine ingredients include lipids (fats), salts, sugars and buffers.

COVID-19 vaccines do not contain eggs, gelatin (pork), gluten, latex, preservatives, antibiotics or aluminum.

People with severe allergies to any of the vaccine ingredients should speak with their physician/allergist about getting the vaccine. Some people with allergies to an ingredient can still be safely vaccinated.

If you get a serious reaction after your first dose, talk to your health care provider about future vaccinations. Sometimes you can still be safely vaccinated, or can received a different vaccine.

Polyethylene glycol (PEG) is in the Pfizer BioNTech and Moderna vaccines. PEG can also be found in laxatives, makeup, skin care products, personal lubricants, toothpastes, and some contact lenses. It is also in cough syrup, over-the-counter medications, and in some food and drinks.

Tromethamine is in the Pediatric Pfizer BioNTech and Moderna vaccine. It helps to make the vaccine stable. Tromethamine can be found in dyes used for CT or MRI scans, medications, cosmetics, perfumes and skin creams.

Polysorbate-80 is in the Novavax (NUVAXOVID), Medicago Covifenz, AstraZeneca/COVISHIELD and Janssen (Johnson & Johnson) vaccines. It is used to hold (or bind) the vaccine ingredients together. Polysorbate-80 can be found in most processed food, sauces, condiments, soups, ice cream, chewing gum, soaps, creams, bath gels, shampoo, body butter, cosmetics, vitamins, heart medication and contraceptives (birth control).

Vaccine Ingredients

Pfizer-BioNTech vaccine

  • active ingredient: messenger RNA (mRNA)
  • lipids, cholesterol, polyethylene glycol [PEG]
  • salts: potassium chloride, monobasic potassium phosphate, sodium chloride, dibasic sodium phosphate dihydrate
  • sugars: sucrose

Pediatric Pfizer-BioNTech vaccine

  • active ingredient: mRNA
  • lipids, cholesterol, polyethylene glycol [PEG]
  • buffers: tromethamin, tromethamin hydrochloride
  • salts: sodium chloride
  • sugars: sucrose

Moderna vaccine

  • active ingredient: mRNA
  • lipids, cholesterol, polyethylene glycol [PEG]
  • buffers: tromethamin, tromethamin hydrochloride
  • salts: acetic acid, sodium acetate
  • sugars: sucrose

AstraZeneca/COVISHIELD vaccine

  • active ingredient: adenovirus vector (ChAdOx1-S recombinant)
  • amino acid: L-Histidine, L-Histidine hydrochloride monohydrate
  • emulsifier: polysorbate 80
  • salts: sodium chloride, disodium edetate dihydrate (EDTA), magnesium chloride hexahydrate
  • sugars: sucrose
  • alcohol: ethanol

Janssen (Johnson & Johnson) vaccine

  • active ingredient: adenovirus vector (Ad26.COV2.S recombinant)
  • buffers/ acidity regulators: citric acid monohydrate, hydrochloric acid, sodium hydroxide, trisodium citrate dihydrate
  • alcohol: ethanol
  • emulsifier: 2-hydroxypropyl-β-cyclodextrin, polysorbate-80
  • salts: sodium chloride

Novavax (NUVAXOVID) vaccine

  • active ingredient: recombinant spike protein with Matrix-M adjuvant
  • non-medical ingredients: disodium hydrogen phosphate heptahydrate, hydrochloric acid (for adjustment of pH), polysorbate 80, sodium chloride, sodium dihydrogen phosphate monohydrate, sodium hydroxide (for adjustment of pH), water for injection
  • for adjuvant: cholesterol, phosphatidylcholine, potassium chloride, potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, sodium chloride

Medicago Covifenz vaccine

  • active ingredient: virus-like particles (VLP) with AS03 adjuvant
  • non-medical ingredients: polysorbate 80, potassium phosphate monobasic anhydrous, sodium chloride, sodium phosphate dibasic anhydrous, water for injection
  • for adjuvant: squalene, vitamin E, polysorbate 80, phosphate buffered saline

COVID-19 risks increase during pregnancy

  • Pregnancy can put you at higher risk for getting very sick and needing to be hospitalized from COVID-19, even if you are healthy.
  • Having COVID-19 while pregnant can increase the chance of giving birth too early (preterm birth), high blood pressure, caesarean birth and having a baby with low birth weight.
  • Pregnant people who are over 35, obese or have certain medical conditions such as heart disease, diabetes, high blood pressure or asthma, have a higher risk of complications from COVID-19.
  • You may be able to receive treatment if you have tested positive or have symptoms of COVID-19 to lower the risk of serious illness and hospitalization. Talk to your health care provider to see if you would be eligible for treatment.

COVID-19 vaccination is strongly recommended if you are planning to become pregnant or are pregnant

  • The Society of Obstetricians and Gynecologists of Canada recommend getting vaccinated as soon as possible if you are planning to become pregnant or are pregnant.
  • Pregnant individuals are able to receive a COVID-19 vaccine at any point in their pregnancy.
  • Getting vaccinated as soon as possible is the safest choice to protect yourself and your baby from the risks of COVID-19 infection.
  • You will make antibodies from the vaccine, which will pass to your growing baby. The antibodies can further protect your baby when born.
  • Staying up-to-date on your COVID-19 vaccines provides good protection from getting very sick or hospitalized due to any variants of the virus.
  • A booster dose is recommended in pregnancy for even better protection for you and your baby.

COVID-19 vaccines are safe in pregnancy

  • The mRNA COVID-19 vaccine and booster doses are safe and strongly recommended in pregnancy and when planning to become pregnant.
  • Several studies with large numbers of pregnant people have shown that vaccination before and/or during any time in pregnancy is safe for you and your baby, and has no impact on pregnancy outcomes.
    • They do not affect fertility (ability to get pregnant), including no effect on egg or sperm.
    • They do not cause miscarriage, premature birth, or high blood pressure.
    • They do not harm the developing baby or cause still birth.
  • Hundreds of thousands of people who are pregnant have been vaccinated.
  • Many people who are pregnant and have been vaccinated are being followed to ensure the vaccine continues to be safe, and there continue to be no concerns.
  • It is safe at any time before, during and after pregnancy, including while breastfeeding.

Vaccinations while breastfeeding

  • Breastfeeding has many benefits for you and your baby including protecting your baby against infections and many illnesses.
  • Getting the COVID-19 vaccine is safe, effective and recommended while breastfeeding.
  • There is no need to avoid starting breastfeeding or to stop breastfeeding to receive the vaccine. It does not disrupt your breastfeeding or have any negative effects on your baby.
  • Getting the vaccine can help protect you from becoming sick with COVID-19 and passing it to your baby.
  • Some studies have shown that antibodies were found in the breastmilk of people who received the COVID-19 vaccine which may protect their infant against COVID-19.

COVID-19 vaccines are recommended even if you already had COVID-19

  • Even if you had a COVID-19 infection, you should still be vaccinated and get the benefit of hybrid immunity.
  • Being infected with COVID-19 can provide some natural protection to you and your baby, but it is unclear how long this protection will last.
  • Getting vaccinated after a recovering from a COVID-19 infection will protect you better and for a longer period of time than someone who had a COVID-19 infection but no vaccine.
  • Your baby will benefit from a longer period of protection against COVID-19 if you stay up to date with the recommended vaccine doses.

Talk to your health care provider if you have questions about getting vaccinated and to understand the benefits of getting the vaccine compared to the risks of getting the COVID-19 infection. For most people, getting a COVID-19 vaccine is the safest choice.

See COVID-19: Where to Get Vaccinated to find a vaccine clinic near you

For more information:

Watch North York General Hospital’s video on getting the COVID-19 vaccine during pregnancy:

Source: North York General Hospital

There is no evidence the vaccines impact fertility, menstrual irregularities, puberty, or normal growth and development.

The main ingredient in the vaccine is mRNA and that lasts in your body for a few days before it is removed from the body. The body develops an immune response in the first few weeks after vaccination. Some may have a temporary change in their menstrual cycle because of this immune response. A menstrual cycle can also temporarily change from everyday life including stress, changes in weight and exercise. The World Health Organization recommends not delaying vaccination if menstruating.

A COVID-19 infection can also affect menstruation. For example, in one study, one out of five patients with confirmed COVID-19 infection had temporary changes in the length of their cycle and the amount of bleeding.

References: (BMJ). (Li et al., 2021)

Vaccinations with health conditions

People with stable health conditions can get vaccinated. Conditions include: diabetes, high blood pressure, heart disease, respiratory diseases, including asthma or COPD, hepatitis B, C and HIV.

People with a weak immune system because of illness, treatment or an autoimmune condition:

  • can get the vaccine safely;
  • should speak to their health care provider before getting vaccinated; and
  • may have lower protection from the vaccine.

People taking medication that make their immune system weak may be able to schedule their vaccine and treatment to get the best protection.


Other helpful resources can be found on the COVID-19: Vaccine Resources page, including an American Sign Language translation of information about COVID-19 vaccines. Also see this video on Getting Ready for Your COVID Vaccine.

The National Advisory Committee on Immunization (NACI) recommends:

  • Pediatric Moderna Spikevax be offered to children aged 6 months to under 5 years of age.
  • Pediatric Pfizer-BioNTech as the preferred COVID-19 vaccine for children aged 5-17 and that Moderna Spikevax may be offered as an alternative to children aged 6-11 with informed consent.

Visit the COVID-19 Infants, Children & Youth Vaccines page for more information.