Last updated: January 14, 2021 at 5:29 p.m.

Anyone 18 years of age or older whose second dose was at least 84 days (three months) ago is eligible for a booster vaccine. Everyone aged 5 and older is eligible to receive a COVID-19 vaccine. Children must be at least 5 years old at the time of vaccination. Find out how and where to get vaccinated.
Everyone is strongly encouraged to get vaccinated. Text “VACCINE” to 1-833-750-0888 for information about vaccines and how to get vaccinated.

COVID-19 vaccines teach our immune system to make antibodies that protect us from the COVID-19 virus. These antibodies will provide protection from getting, spreading, and becoming severely sick with COVID-19. None of the vaccines contain COVID-19 and cannot give us the virus.

The Pfizer-BioNTech and Moderna vaccines are called ‘messenger RNA’ or ‘mRNA’ vaccines. They use mRNA to give our cells instructions to make antibodies. The mRNA does not change our DNA. Watch a video from the Government of Canada for more information on how mRNA vaccines work.

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

mRNA and viral vector vaccines use technology that has been around for over 10 years. The mRNA provides instructions to our immune system to make antibodies.

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. To be considered fully vaccinated, The Pfizer-BioNTech, Moderna and AstraZeneca vaccines require two doses, and one dose for the Janssen vaccine.

Studies on how long protection lasts in the general population are ongoing and booster doses may be recommended in the future.

Vaccine development and approval process

COVID-19 vaccines were developed without skipping any safety steps. This was possible because of advances in science, international collaboration and increased funding.

The COVID-19 vaccines used in Ontario have been fully approved by Health Canada. They have met the same safety and quality standards required for all vaccines, and have been tested in large clinical trials to show they are safe and they work. No steps were skipped in the approval process.

Canada has one of the best vaccine safety programs. Vaccines must pass many safety tests before they are considered to be safe for people. Health Canada authorizes vaccines only when there is sufficient scientific and clinical evidence that they are safe, effective, and are manufactured to the highest quality standard. There are several systems in place to monitor the vaccine’s safety.

Watch a video from the Government of Canada to learn more about how COVID-19 vaccines are developed.

Interval between first and second doses

The optimal interval between the first and second dose is eight weeks for a mRNA vaccine and at least eight weeks for an AstraZeneca vaccine.

  • This interval is recommended because it allows for a stronger immune response to the second dose, and it is associated with a lower rate of side effects.
  • Data suggests that protection can be improved when the interval between the first and second doses are extended beyond the original manufacturer’s recommended interval (e.g., 21 days between 1st and 2nd dose of a Pfizer-BioNTech COVID-19 vaccine).
  • This interval appears to provide optimal protection, while minimizing the time at risk of infection due to having protection from only one dose.
  • Two doses at eight weeks apart continues to protect adults and children from severe illness ensuring a strong immune response against variants, such as Delta and Omicron, plus any possible new variants in the future.
  • Individuals may choose to speak with their primary care provider about what interval is best for them considering individual risks. The authorized interval may still be used.
  • Interruption of a vaccine series resulting in a greater interval between doses than recommended does not require re-starting the series.

Reference: Ministry of Health (2021). COVID-19 Vaccine Administration, Version 2.0.

Vaccinations and previous COVID-19 infection

People who have had COVID-19 in the past should still get vaccinated. Natural immunity from having COVID-19 may not last long and may not protect against COVID-19 variants. Get vaccinated to stay protected.

Anyone with COVID-19 symptoms, including fever, should not go to a vaccine clinic. Please wait until you are no longer in self-isolation AND your symptoms have gone away.

  • Omicron is a new variant of concern (VOC) and has many mutations compared to past variants, such as Delta.
  • Omicron spreads more easily, meaning it infects more people faster.
  • Vaccines (at least two doses and booster) still work against Omicron and continue to be the best tools for preventing severe COVID-19 infection, hospitalization and death.
  • We continue to collect and closely monitor data to show if the Omicron variant will impact adults and children any differently than past variants of COVID-19.
  • Two doses of vaccine still protect very well against other variants, such as Delta, and possible new future variants.


What we can do to stay protected

Continue to follow public health measures and get vaccinated as soon as you can:

  • Getting a booster, with an mRNA vaccine (Pfizer or Moderna), raises the effectiveness of the vaccines and provides significant protection against severe illness.
  • mRNA vaccines are interchangeable – take the vaccine that is available to you, regardless of previous two doses.
  • It is strongly recommended that children ages 5 and over get vaccinated as soon as possible.

Like all medicine, some people may have side effects from the vaccine. If these side effects happen they usually last for one to three days.

Common side effects:

  • sore arm
  • headache
  • feeling tired
  • muscle or joint pain
  • fever
  • chills
  • feeling like you are going to vomit (nausea) and/or vomiting

Some side effects are more common after the second dose of the Pfizer and Moderna vaccines.

Learn more about rare side effects with the AstraZeneca/COVISHIELD vaccine and the mRNA vaccines below.

After your vaccine please stay at the clinic for 15 minutes. You will be monitored for any reactions. In very rare cases, serious allergic reactions (anaphylaxis) can occur. Allergic reactions can be treated and are usually temporary. Get medical attention if you get allergic reactions such as hives, itching, swelling of the face and throat, and/or trouble breathing.


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 allergies to any of the vaccine ingredients should not get the vaccine. If you get a serious reaction after your first dose, do not get the second dose. Talk to your health care provider if you are unsure about which ingredients you are allergic to.

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 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

Vaccinations while breastfeeding

Breastfeeding has many benefits for you and your baby including protecting your baby against many illnesses. The Society of Obstetricians & Gynecologists of Canada recommends vaccination for pregnant and breastfeeding people who do not have any medical conditions that prevent them from getting the vaccine.

There is no need to avoid starting breastfeeding or to stop breastfeeding to receive the vaccine. 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. More studies are needed to determine how much protection this offers. While people who are breastfeeding were not included in most of the vaccine clinical trials, the vaccines are considered safe for people who are breastfeeding because of the way the vaccines work in the body.

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.

For more information:

Vaccinations while pregnant

Pregnant individuals are able to receive a COVID-19 vaccine at any point in their pregnancy. Many people who are pregnant have gotten very sick from COVID-19 requiring hospitalization and critical care. Getting vaccinated is safe and an important way to be protected in pregnancy.

Talk to your doctor or midwife if you have questions about getting vaccinated and to understand benefits of getting the vaccine compared to the risks of getting the COVID-19 infection. For many people, getting a COVID-19 vaccine is the safest choice.

The Society of Obstetricians & Gynecologists of Canada also recommends pregnant people get vaccinated in pregnancy. Many pregnant people who get COVID-19 can have mild symptoms. However, especially with the new variants spreading in Ontario, some can get very sick and develop respiratory complications that need care in the hospital. Giving birth too early in pregnancy (preterm birth) may be more common.

Vaccines can protect against these variants and lower the risk of severe illness while pregnant. All COVID-19 vaccines are safe in pregnancy and are being used around the world.

If you are planning on becoming pregnant, it is recommended to get both doses of the vaccine ahead of pregnancy (where possible) when it’s available to you. There is no evidence that fertility problems are a side effect of any vaccine.

If you are pregnant or become pregnant soon after getting the first dose of the vaccine you will have to decide if you should get the second dose. The decision should be made by looking at the risks of not being completely vaccinated during pregnancy.

While COVID-19 vaccine clinical trials did not include people who were pregnant or breastfeeding, many people who are pregnant and have been vaccinated are being followed to ensure the vaccine continues to be safe.

Before going for your clinic appointment, talk to your health care provider about:

  • the risks and benefits of the vaccine
  • the risks of getting a COVID-19 infection during pregnancy
  • the risks of a COVID-19 infection during pregnancy
  • how clinical trials and real world data can provide evidence on the safety of the vaccines in pregnancy.

Please note:

  • A letter from a health care provider is not required for vaccination.
  • You are encouraged to receive your second dose as soon as you are eligible to ensure maximum protection against COVID-19.

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 change in their menstrual cycle that is temporary, 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. There are no long term impacts on fertility, puberty or growth and development from the vaccine.

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.

Vaccinations for people with disabilities

People of all levels of ability can get COVID-19. Some people with disabilities may be at higher risk of getting COVID-19. For example, those who require daily service provision or who reside in congregate care settings may be at higher risk.

Most people should get a COVID-19 vaccine. Ask your doctor or healthcare provider if you should get a COVID-19 vaccine.


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.

On November 19, 2021, Health Canada authorized the use of Pediatric Pfizer-BioNTech and the National Advisory Committee on Immunization (NACI) recommends a complete series (two doses) of the Pfizer-BioNTech COVID-19 vaccine. This pediatric COVID-19 vaccine is safe and effective for the 5 to 11 age group. Visit COVID-19 Children and Vaccines page for more information.

Name Technology Age group Dose schedule Recommended Interval (time between 1st and 2nd dose)


Pfizer BioNTech mRNA 12 years + 2 doses 8 weeks Available
Pediatric Pfizer BioNTech mRNA 5-11 years 2 doses 8 weeks Available

Note: Pfizer-BioNTech is recommended for 12-29 year olds.

mRNA 12 years + 2 doses 8 weeks Available
AstraZeneca/COVISHIELD* Viral vector 18 years + 2 doses At least 8 weeks Only by referral
Janssen* Viral vector 18 years + 1 dose Not applicable Only by referral

* Note: Referral is required from an allergist/immunologist or another specialist where a confirmed allergy exists to components of the mRNA vaccines or there are concerns in accessing an mRNA vaccine.

All adverse events investigated by Toronto Public Health are forwarded to the province, then to Public Health Agency of Canada. Adverse events are also compared internationally.

The Public Health Agency of Canada, Health Canada and Public Health Ontario are closely monitoring rare reports of potential myocarditis/pericarditis following a COVID-19 mRNA vaccine, including those among youth. In Canada, there have been a small number of these reports and no conclusive association has been established between myocarditis/pericarditis and mRNA vaccines at this point in time.

To date, Public Health Ontario has received reports of a small number of cases of myocarditis/pericarditis among youth 12 to 17 years of age in Ontario. At this early time, the small number of cases seen among adolescents to date in Ontario have been mild and have resolved without any concerns about potential long-term complications.

On August 27, 2021 Health Canada authorized the use of the Moderna COVID-19 vaccine for ages 12 and over. After a thorough review of the current global and Canadian experience and vaccine safety surveillance data, Ontario will continue using the Pfizer-BioNTech vaccine for youth ages 12-17 (including those turning 12 in 2021). In this age group, there is more experience and possibly a lower rate of myocarditis/pericarditis to date with this vaccine.

As of September 29, 2021, Ontario’s Chief Medical Officer of Health recommends that the Pfizer-BioNTech vaccine is preferred for individuals aged 18-24 years old. 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. The majority of reported cases have been mild with individuals recovering quickly, normally with anti-inflammatory medication. Symptoms have typically been reported to start within one week after vaccination, more commonly after the second dose. Individuals 18-24 years old can still receive the Moderna vaccine with informed consent.

As of November 19, 2021, Health Canada authorized the use of Pediatric Pfizer-BioNTech and the National Advisory Committee on Immunization  (NACI) recommends a complete series of the Pfizer-BioNTech COVID-19 vaccine. This vaccine is safe and effective for the 5–11 age group.

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

Myocarditis and Pericarditis

  • Myocarditis and pericarditis are types of inflammation in different parts of the heart.
  • 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.
  • Some people who have had a COVID-19 infection have also experienced myocarditis.

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 an mRNA vaccine:

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

Vaccine Benefits

Vaccination continues to be recommended for everyone 5 years of age and older, considering the long-term effects and serious complications related to a COVID-19 infection.

For individuals who experience myocarditis/pericarditis after receiving a COVID-19 mRNA vaccine, the decision to administer a second dose of the vaccine should be made on a case-by-case basis, until further data on this condition and the possible causality between mRNA vaccines and myocarditis/pericarditis is available.

Speak to your health care provider if you have questions about getting a mRNA vaccine.

More Information

The viral vector vaccines approved in Canada are: AstraZeneca (also known as COVISHIELD) and Janssen (also known as Johnson and Johnson).

The National Advisory Committee on Immunization (NACI) strongly recommends mRNA vaccines (Pfizer-BioNTech, Moderna) for all eligible age groups. It has shown to be safer and more effective against COVID-19 infection than viral vector vaccines. The Ministry of Health issued a preferential recommendation for the use of Pfizer-BioNTech COVID-19 vaccine for individuals 18-24 years of age.

Anyone receiving an authorized viral vector COVID-19 vaccine (AstraZeneca/COVISHIELD or Janssen) should consult a health care provider to help make an informed decision about:

  • Individual risks and very rare reactions that have been 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 administration of the AstraZeneca COVID-19 vaccine until further notice. This decision was based on input from the (NACI), Public Health Ontario and the Science Table.

Already received a first dose of AstraZeneca/COVISHIELD

If you already received a first dose of the AstraZeneca or COVISHIELD vaccine, it is important to remember that serious side effects are rare events. It is established that 28 days after you received the vaccine, the risk of severe side effects has passed. 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 as safety and effectiveness have not yet been established.
  • 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 receive an mRNA COVID-19 vaccine.
  • Clinical trials showed that beginning two weeks after the single dose, the Janssen COVID-19 vaccine lowered the chance of getting sick from COVID-19 by 67% and of getting seriously ill by 77%.

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