Frequently Asked Questions About the COVID-19 Vaccine

These are answers to COVID-19 vaccine questions for residents and workers in the Eastern Ontario Health Unit (EOHU) region.

If you wish to speak to a qualified professional about your questions regarding the COVID-19 vaccine, you can Book a VaxFacts appointment at 416-438-2911 ext. 5738 or click here.

General questions about the COVID-19 vaccine

Questions about COVID-19 vaccine safety

Questions about the bivalent vaccine

Questions about how and when the vaccine is being distributed

General questions about the COVID-19 vaccine

What COVID-19 vaccines are currently approved and available in Ontario?

The following COVID vaccines are approved and available in Ontario as primary series vaccines or as boosters:


  • Pfizer-BioNTech vaccine for children aged 6 months to 4 years
  • Moderna vaccine for children aged 6 months to 5 years
  • Pfizer-BioNTech vaccine for children aged 5 to 11 years (Pfizer is the recommended vaccine for ages 5-11 years – see exception below*)
  • Pfizer-BioNTech vaccine for ages 12 years and over (Pfizer is the recommended vaccine for ages 12-29 years)
  • Moderna vaccine for ages 6 years and older
  • Janssen (Johnson & Johnson) vaccine for ages 18 years and older
  • Novavax vaccine for ages 18 years and older


  • Pfizer-BioNTech bivalent vaccine for ages 5 years and older (Pfizer bivalent is the recommended booster for ages 5-17 years)
  • Moderna bivalent vaccine for ages 18 years and older (also available for ages 12 to 17 years with moderate to severe immunocompromising conditions)
  • Janssen (Johnson & Johnson) vaccine for ages 18 years and older
  • Novavax vaccine for ages 18 years and older

* Children who are 5 years old and who have started (but not completed) their primary vaccine series using a Moderna vaccine must complete their series using the Moderna vaccine for 6 months to 5 years of age. Mixing of Pfizer and Moderna vaccines is not recommended for the primary pediatric vaccine series due to their different dosing instructions.

Which vaccines am I eligible for?

Please see the provincial website for more information about vaccine eligibility and vaccine doses.

Are vaccines interchangeable?

For individuals aged 6 and over: Yes, the Pfizer-BioNTech and the Moderna vaccines can be administered interchangeably (one for the first dose and another for the second, third or fourth) safely, without increased risk or decreased efficacy of the vaccine. They can both also be received safely as a second dose by individuals who received the AstraZeneca vaccine for their first dose.

The Provincial Booking System no longer specifies the type of vaccine (Pfizer-BioNTech or Moderna) to be administered when booking an appointment. Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines are administered at COVID-19 vaccination clinics throughout the EOHU region. Depending on vaccine availability at the time of the appointment, individuals attending clinics may not receive the same vaccine they received in previous doses. Rest assured that the best vaccine to receive is the first one that is available for your age group.

For children under age 6: Mixing of Pfizer and Moderna vaccines is not recommended for the primary pediatric vaccine series due to their different dosing instructions. To complete the primary vaccine series for children under age 6, the Moderna pediatric vaccine requires 2 doses of Moderna and the Pfizer pediatric vaccine requires 3 doses of the Pfizer vaccine.

What is an mRNA vaccine?

mRNA vaccines are a new type of vaccine; however, researchers have been studying and working with these vaccines for quite some time. mRNA vaccines teach our cells how to make a protein that will trigger an immune response. 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.

Like all vaccines, people who are vaccinated gain protection without ever having to risk the serious consequences of getting sick from being exposed to the virus. People also can't get COVID-19 from the vaccine itself. mRNA vaccines do not use the live virus that causes COVID-19.

Both the Pfizer-BioNTech and Moderna vaccines are mRNA vaccines.

Is the COVID-19 vaccine mandatory?

The COVID-19 vaccine is not mandatory; however, it is strongly recommended to help protect against the COVID-19 virus, especially for those who are at higher risk of serious illness or death, and for those who work directly with vulnerable people. In addition, some workplaces may have policies that require workers to be vaccinated.

Can I still get or transmit COVID-19 after being vaccinated?

While you can still get COVID-19 after being vaccinated, the vaccines are shown to reduce the symptoms and the severity of illness related to COVID-19.

This in turn reduces transmission because, with most variants, vaccinated individuals who get infected tend to have a smaller amount of the virus present in their bodies and release less of it while they talk, exhale or do other normal daily activities. It is important to continue taking public health measures such as hand washing and staying home if you are sick.

Why should I get vaccinated if COVID-19 infection has a high survival rate?

COVID-19 can be a serious illness for many people. It is also possible to be re-infected with a different variant of COVID-19 after a COVID-19 infection. Some variants are more transmissible; therefore it is important to stay up to date with COVID-19 vaccination by receiving all doses recommended.

For some people, symptoms can last for months. These people are called long haulers. The virus can even damage the heart, brain and lungs and increase the risk of long-term health problems. Even young, healthy people can feel unwell for weeks to months following the COVID-19 infection.

The short-term side effects of the COVID-19 vaccine are less than the risk and potential long-term health damage caused by the COVID-19 virus.

If I tested positive for COVID-19 in the past, should I still get the vaccine?

Yes. If you’ve already had COVID-19, you should still get vaccinated. Keeping your vaccines and boosters up to date helps protect you from reinfection, or from severe outcomes if you do become infected again. While infection alone provides some protection, vaccination combined with previous infection provides stronger and longer protection against future reinfection and serious illness.

You should wait to get the vaccine if you are sick or have COVID-19 right now. For information on how long to wait between COVID-19 infection and vaccination, see the Ministry of Health recommendations: If you’ve had COVID-19. More detailed information can also be found in the Ministry of Health’s document: COVID-19 Vaccine Guidance.

Are the existing vaccines effective against the new variants of COVID-19?

The vaccines have been shown to be effective against the new variants for individuals who are up to date with their vaccination. Receiving boosters is highly recommended to provide an improved immune response against COVID-19 and its variants.

The vaccines are shown to reduce the symptoms and severity of illness in individuals who are up to date with their vaccination. This in turn reduces transmission because, with most variants, vaccinated people who get infected tend to have a smaller amount of the virus present in their bodies and release less of it while they talk, exhale or do other normal daily activities.

Why do some populations have a shortened interval between vaccines?

There are some populations who need the additional increase in protection by receiving their COVID-19 dose at a shortened interval. These groups may be at higher risk because they have specific medical conditions, live in a congregate setting with other high-risk individuals (e.g. long-term care homes), or live in communities that are very challenging to reach with medical care.

The National Advisory Committee on Immunization (NACI) recommends that the following populations receive their doses at a shortened interval:

  • Residents of long-term care homes, retirement homes, elder care lodges and assisted living facilities
  • Transplant recipients (including solid organ transplants and hematopoietic stem cell transplants)
  • Individuals with malignant hematologic disorders and non-hematologic malignant solid tumors receiving active treatment (chemotherapy, targeted therapies, immunotherapy), excluding individuals receiving solely hormonal therapy or radiation therapy
  • Individuals undergoing hemodialysis or peritoneal dialysis
  • First Nations and Indigenous populations, and their partners and household members (including non-Indigenous partners and household members) at the interval indicated in the product monograph

What is considered fully vaccinated?

An individual is considered fully vaccinated 14 days after having received one of the following:

  • The full primary series of a COVID-19 vaccine authorized by Health Canada, or any combination of such vaccines, or
  • One or two doses of a COVID-19 vaccine not authorized by Health Canada, followed by one dose of a COVID-19 mRNA vaccine authorized by Health Canada, or
  • Three doses of a COVID-19 vaccine not authorized by Health Canada.

However, the protection offered by COVID-19 vaccines decreases over time, requiring the need to receive booster doses. It is therefore highly recommended that individuals stay up to date with their vaccination to maintain a high level of protection against COVID-19.

How do I know if I’m up to date with my COVID-19 vaccines?

While the COVID-19 vaccines authorized by Health Canada all provide a high level of protection against illness and hospitalization from COVID-19, the level of protection they provide decreases over time, especially in older individuals.

This means that receiving a primary series of a COVID-19 vaccine is simply not enough to protect you over time from COVID-19 and its variants like Omicron. It is therefore recommended that individuals stay up to date with their vaccination by receiving all recommended booster doses for which they’re eligible.

Click here for more information about the primary vaccine series and booster doses you may be eligible for, depending on your age, health status, and which vaccines you have received.

How many booster doses should/can I receive?

At this time, there is no specific recommended number of booster doses; rather, eligible individuals 5 years of age and older should consider receiving another dose if it has been 6 months or more since your last dose. This will help provide your body with a high level of protection against the severe effects of COVID-19 infection.

Questions about COVID-19 vaccine safety

Is the vaccine safe?

Yes, all vaccines in use in Canada have been approved by Health Canada. Health Canada only approves a vaccine if very robust scientific data and evidence show that it is both safe and effective. After approval, Health Canada and the Public Health Agency of Canada continue to monitor the ongoing safety and effectiveness of all approved vaccines in Canada.

For detailed information on the vaccine and the evidence behind the vaccine approval process, visit the Government of Canada’s website.

What are the most common side effects from the COVID-19 vaccine?

Some people may experience side effects from the vaccine, but these will likely be mild to moderate and resolve after a few days. The most common side effects include pain at the injection site, headache, fatigue, muscle and joint pain, chills and fever.

It is important to receive all recommended doses even if you experience mild or moderate side effects.

Are there any serious side effects?

Serious side effects are very rare. They include:

  • Hives
  • Swelling of mouth and throat
  • Trouble breathing, hoarseness or wheezing
  • Fever over 40C or 104F
  • Seizures
  • Very rare cases of myocarditis and pericarditis following vaccination with COVID-19 mRNA vaccines have been reported. Symptoms include:
    • Chest pain
    • Shortness of breath
    • Palpitations, or feeling a rapid or abnormal heart rhythm

If you experience serious side effects, you should seek medical help immediately. Do not get a second dose or a booster dose of the vaccine if you have serious side effects following the first dose. Speak to your healthcare provider for advice.

Can I get COVID-19 from the shot?

No. There is no live COVID-19 in the vaccine.

Will the COVID vaccine change my DNA?

No, the vaccine does not and cannot change your DNA in any way.

I am pregnant. Can I get the COVID-19 vaccine?

If you are pregnant, you may choose to receive the COVID-19 vaccine at any time during your pregnancy. It is recommended, but not required, that you discuss the vaccine with your treating healthcare provider, or with a healthcare provider familiar with your pregnancy. However, a letter from a healthcare provider is not required for vaccination.

To help you decide, see this resource from the Provincial Council for Maternal and Child Health.

If you are pregnant and under 18 years old, please contact your primary care provider or call the health unit at 613-933-1375 or 1-800-267-7120 to discuss what is the best option for you.

Who should not get the vaccine?

The following people should not get the COVID-19 vaccine:

  • People who have allergies to the COVID-19 vaccine ingredients should consult their health care provider for an assessment.
  • People who have had a serious allergic reaction to the COVID-19 vaccine (first dose) should not receive a second dose or booster dose of the COVID-19 vaccine until they have been advised by public health.
  • Anyone who is sick or has COVID-19 should wait to receive the vaccine.

Individuals with compromised immune systems or autoimmune disease are strongly encouraged to speak with their treating health care provider regarding timing of vaccination in relation to therapy or treatment for their condition.

For more information, see COVID-19 Vaccination Recommendations for Special Populations.

If I had a reaction to a different vaccine in the past, can I still get the COVID-19 vaccine?

Check with your doctor or healthcare provider if you have had a serious allergic reaction to a vaccine in the past. They will look at your medical records and help you make the decision.

Should I get the COVID-19 vaccine if I have food or seasonal allergies?

Please talk with your physician or healthcare provider to learn if it is safe for you to receive the COVID-19 vaccine.

I just got vaccinated for something else. Can I still get the COVID-19 vaccine now?

For adults and children aged 6 months and older, the National Advisory Committee on Immunization (NACI) recommends that COVID-19 vaccines may be given at the same time as, or any time before or after, the flu shot or other vaccines, including live, non-live, adjuvanted or unadjuvanted vaccines.

Should we be concerned about myocarditis and/or pericarditis following a mRNA COVID-19 vaccine?

Cases of myocarditis and/or pericarditis following immunization with COVID-19 vaccines have been reported in a small number of people in Canada and internationally. These reports are very rare and investigations into the association between myocarditis/pericarditis and mRNA vaccines continue.

Health Canada reassures Canadians that COVID-19 vaccines continue to be safe and effective at protecting them against COVID-19. The benefits of COVID-19 vaccines continue to outweigh their potential risks, as scientific evidence shows that they reduce deaths and hospitalizations due to COVID-19. The Government of Canada encourages people to get vaccinated and to complete their vaccine series as soon as they are eligible.

Consult the Advisory:

Questions about the bivalent vaccine

What is the bivalent vaccine? How is it different from the other vaccines?

Bivalent vaccines protect against two strains of a virus, or two different viruses, rather than using separate vaccines for each. The Pfizer and Moderna bivalent COVID-19 vaccines are formulated to protect against both the original strain of the COVID-19 virus and the Omicron variants, and will help provide more protection against infection and serious illness and complications from COVID-19 infection. Preliminary study results indicate that the bivalent vaccine provides good protection against the BA4 and BA5 Omicron subvariants. The original Moderna and Pfizer vaccines are monovalent, as they only contain the original strain of COVID-19.

Are bivalent vaccines a new type of vaccine?

Bivalent, and other multivalent vaccines are not new technology and have been around for decades. Bivalent and multivalent vaccines are a safe and effective way to protect against multiple viruses or strains of a virus in one vaccine. You have probably received at least one type of bivalent or multivalent vaccine already! Some multivalent vaccines you may be more familiar with include the MMR or MMRV vaccines (which protect against measles, mumps, rubella, and varicella (chicken pox)), the DTaP and Tdap vaccines (which protect against tetanus, diphtheria and pertussis), and even the flu vaccine (which can protect against multiple strains of flu viruses).

Can I get the bivalent COVID-19 vaccine as my first or second dose?

No. At this time, the bivalent COVID-19 vaccine is only available as a booster dose for individuals aged 5 and older. First and second doses (primary series vaccines) continue to be the Pfizer and Moderna monovalent vaccines.

When should I get the bivalent COVID-19 vaccine?

Like with other booster doses, it is recommended you wait 6 months from your last dose, and a minimum of 3 months before you receive the bivalent COVID-19 vaccine. If you have recently had COVID-19, you should wait 3 months from your infection to receive your next dose.

To help prevent severe illness and complications from COVID-19, it’s recommended you get your next dose as soon as you are eligible.

Is one bivalent vaccine better than the other?

No, both bivalent vaccines provide increased protection against the Omicron strains compared to the original mRNA vaccines and the best bivalent vaccine is the first one that is offered to you. Waiting to receive a different vaccine may leave you more exposed to COVID-19 and serious illness.

Do I have to get the bivalent vaccine for my booster?

For booster doses, the bivalent vaccines are recommended over the original mRNA vaccines. However, you can ask to receive the monovalent vaccine as a booster. If you are eligible, the bivalent booster will be the first vaccine offered to you, as it provides better protection against the Omicron strains.

How can I book an appointment?

See How and Where to Get a COVID-19 Vaccine for a full list of options, including booking vaccine appointments or receiving your vaccine at a walk-in clinic.

Questions about how and when the vaccine is being distributed

When will I be able to get the COVID-19 vaccine?

COVID-19 vaccines are currently available to all eligible individuals 6 months of age or older. Consult the How and Where to Get a COVID-19 Vaccine page for information on vaccine dose eligibility, and vaccination clinic locations and dates throughout the EOHU region. COVID-19 vaccines are also available at participating pharmacies.

Should I wait for my preferred choice of vaccine?

No. All COVID-19 vaccines that have been approved by Health Canada are effective. It is important to get the vaccine which is recommended for you and for which you are eligible, when it is offered to you – regardless of brand or type.