COVID-19 Vaccine Frequently Asked Questions

What is the COVID-19 vaccine?

A vaccine is a medicine that gets your immune system to produce antibodies. Antibodies are proteins trained to recognize the virus and protect your immune system against it. They can be produced after getting vaccinated, but also by being infected with the virus.

After getting vaccinated for COVID-19, you develop some immunity to the virus, without having to get COVID-19 first. This is what makes vaccines such powerful medicine. Unlike most medicines, which treat or cure diseases, vaccines keep you from getting sick in the first place.

How were the vaccines approved for use in Canada?

Drugs, including vaccines, are regulated under the Food and Drugs Act and regulations. They must meet the regulatory requirements for safety, efficacy and quality before they can be approved for use and distribution in Canada. Health Canada is responsible for approving vaccines.

Before approving a vaccine, they look carefully at the:

• scientific and clinical evidence — including results of clinical trials — to determine if a vaccine product is safe, effective and manufactured to the highest quality.
• safety and efficacy of the vaccine to determine that
  • there are no concerns;
  • the vaccine can trigger a strong enough immune response to protect against disease;
  • the benefits outweigh the risks.
• manufacturing process to make sure the manufacturer can carry out the necessary quality controls for the vaccine.

If there is not enough evidence to support the manufacturer’s safety, effectiveness or quality claims, Health Canada will not authorize the vaccine and the product cannot be sold in Canada.

Find out more about Health Canada’s:

• vaccine approval process
• review of COVID-19 vaccines

The vaccines were developed so quickly. How can I be sure they are safe?

Creating a new vaccine usually takes years. However, the COVID-19 vaccines were developed quickly for many reasons, including:

• being informed by decades of research on other strains of coronavirus before COVID-19 (such as Middle East Respiratory Syndrome (MERS) and Sars-CoV, also known as SARS).
• advances in science and technology.
• scientists, health professionals, researchers, industry and governments around the world all working together.
• more dollars were quickly put towards the creation of these vaccines.

Before any vaccines are available in Ontario, they:

• undergo intense clinical trials to make sure they are safe and effective.
• are evaluated and authorized for use by Health Canada, using very high standards.

Ontario makes sure vaccines remain safe by:

• transporting and storing vaccines safely and securely at required conditions and temperatures.
• finding safe clinic spaces to vaccinate people and providing the required training to those giving the vaccines.
• monitoring for any adverse reactions or side effects that may take place after vaccination, taking appropriate measures and working with the federal government, other provinces and territories.

Once a vaccine is in use, Canada has a strong vaccine safety monitoring system to tell public health authorities about changing trends or unusual reactions that were not reported before.

Read more information on vaccines and vaccine authorization updates from the Government of Canada.

What is an mRNA vaccine and how does it work?

mRNA stands for Messenger Ribonucleic Acid. mRNA vaccines, such as Pfizer and Moderna, give cells in your body instructions to make part of a harmless a protein from the COVID-19 virus.

Once the cells make the protein, the instructions are broken down. The cells display the pieces of protein they have created, then your body recognizes that protein as foreign and develops an immune response.

This response will recognize and fight the virus that causes COVID-19 if you are exposed to it later on.

mRNA vaccines do not change or affect your own DNA.

What is a viral vector-based vaccine and how does it work?

The Johnson & Johnson COVID-19 vaccine, an Ebola vaccine, and many vaccines used for animals are examples of viral vector-based vaccines.

These vaccines have a vector, which, in the COVID-19 vaccine, is a non-COVID-19 virus that has become inactive and harmless. The vector delivers "blueprints" to some of our cells, providing instructions to build a protein of the virus that causes COVID-19.

The cells build and display that protein, which our immune cells notice as being unfamiliar. Our immune cells produce an immune response and remember that unfamiliar protein so they can recognize and fight against future COVID-19 infections.

What is a protein subunit vaccine and how do they work?

Protein subunit vaccines, such as Novavax Nuvaxovid^®, contain harmless and purified pieces (proteins) of the virus, which have been specifically selected for their ability to trigger immunity.

Protein subunit vaccines are already used for other diseases. An example of an existing protein subunit vaccine is the one for hepatitis B.

Why do I need so many COVID-19 vaccines?

Up to date vaccines restore protection that may have decreased since your last dose and keep you protected from severe illness and/or hospitalization from COVID-19.

Why should I get vaccinated if the COVID-19 infection has a 99% survival rate?

COVID-19 can be a serious illness for many people, and for some people, symptoms can last for months. The virus can even damage the heart, brain, 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 damages caused by the COVID-19 virus.

Will the COVID-19 vaccine prevent you from getting COVID-19, or will it decrease the severity of the virus if you get infected?

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

The most common side effects are mild to moderate. They include:

• pain at the injection site;
• headache;
• fatigue;
• muscle and joint pain;
• chills;
• fever.

I had side effects with one of my COVID-19 vaccines, should I get further doses to stay up to date?

Mild to moderate side effects such are relatively common and if you experience them, it is still safe to receive your next dose of COVID-19 vaccine. The most common side effects include:

• pain at the injection site;
• headache;
• fatigue;
• muscle and joint pain;
• chills;
• fever. 

Allergic or severe reactions to the COVID-19 vaccine are rare. If you experienced an allergic or severe reaction to a vaccine dose, please report it to your health care provider or our non-emergency vaccine intake line at 705-474-1400 ext. 5252. You will be provided with guidance on receiving future doses.

Are there any serious side effects?

Serious side effects are very rare. However, should you develop any of the following reactions within three days of receiving the vaccine, seek medical attention right away or call 911 if you are severely unwell:

• Hives;
• Fever over 40°C or 104°F;
• Convulsions or seizures;
• Very pale colour and serious drowsiness;
• Swelling of mouth and throat;
• Trouble breathing, hoarseness or wheezing;
• Other serious symptoms (e.g., “pins and needles” or numbness).

Rare side effects can be reported to our non-emergency vaccine intake line at 705-474-1400 ext. 5252.

If someone gets one or more of the side effects from the vaccine will they need to self-isolate and/or get tested since the side effects are on the COVID-19 symptom list?

Some of the side effects of the vaccine are similar to symptoms of COVID-19 infection. However, side effects from the vaccine should only last a day or two and go away on their own.

If you have mild symptoms within the 48 hours after vaccination, there is no need to self isolate, if symptoms:

• involve only headache, fatigue, or muscle aches/joint pain (pain, redness, and swelling at the injection site are not symptoms compatible with COVID-19).
• only began after vaccination, and there has been no exposure to someone with COVID-19 symptoms in the last ten days.

If you have the above symptoms you are encouraged to wear a mask when out in public and physically distance from others if possible.

If you have decreased or loss of smell or taste or more severe symptoms including fever and/or chills, or a new or worsening cough, then you are advised to self-isolate until your symptoms have been resolving for 24 hours (48 hours if the symptoms are gastrointestinal). It is possible that you may have COVID-19 or another infection.  

Seek medical attention, which may include a COVID test if symptoms are persisting longer than 48 hours after your vaccination, or you really aren’t feeling well and are having difficulty looking after yourself at home.

What are the long-term side effects of the vaccine?

The risk of vaccine side effects developing after a few weeks is extremely unlikely.  Vaccines do not persist in the body, they get broken down. Our experience with decades of vaccine monitoring, is that no licenced vaccine has shown to have long-term safety problems.

Manufacturers are continuing to follow clinical trial participants. They must communicate any potential safety concerns to Health Canada (Health Canada, 2020). Health professionals are required to report adverse events following immunization (AEFIs) to their local Health Unit so that these reactions can be compiled by Public Health Ontario.

Does the COVID-19 vaccine cause blood clots?

The viral vector vaccines, including the Johnson & Johnson/Janssen vaccine have been associated with rare blood clots. These are a specific type of blood clot called VITT (Vaccine-Induced Immune Thrombotic Thrombocytopenia), which does not tend to cause strokes, pulmonary embolism (PE) or deep vein thrombosis (DVT). mRNA COVID vaccines have not been associated with an increased risk of blood clots.

mRNA vaccines remain the preferred COVID-19 vaccine type for most people, given their superior efficacy and safety profile.

Does the vaccine cause myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the tissue surrounding the heart)?

Cases of myocarditis and/or pericarditis in people who received the COVID-19 vaccine are very rare. 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.

Can I get COVID-19 from receiving the vaccine?

No, the vaccine does not cause COVID-19; however, it does take an average of two weeks for the vaccine to actually protect against COVID-19, so it’s possible someone could still get the virus after receiving the vaccine if they don’t follow public health measures.

Do all my doses need to be the same brand?

No. The National Advisory Committee on Immunization has confirmed getting different brands of COVID-19 vaccine is safe and effective at protecting you and your loved ones from COVID-19 and variants.

I’m pregnant. Should I get the vaccine?

Yes. It's recommended that all eligible pregnant individuals, at any stage in pregnancy, get vaccinated as soon as possible. Unvaccinated pregnant individuals are at higher risk for hospitalization, ICU admission, mechanical ventilation and death compared to non-pregnant individuals. COVID-19 infections during pregnancy can be very serious, and the benefits of vaccination outweigh the risks.

Should I get the vaccine if I'm breastfeeding?

Yes. COVID-19 vaccination is safe, effective and recommended for individuals who are breastfeeding. The mRNA from vaccines doesn’t transfer in breast milk, but vaccinated breastfeeding individuals produce antibodies which fight the virus that causes COVID-19. These antibodies do transfer in the breast milk and provide protection to the infant. Read more.

Is the vaccine mandatory?

Some places, such as hospitals, home and community service providers and non-essential services may require employees, contactors, students and volunteers to be up to date with COVID-19 vaccinations. 

How long does it take after I'm vaccinated to be protected against COVID-19?

Studies have shown that the vaccine starts to take effect approximately 14 days after the first dose, and provides even more protection seven to 14 days after the second dose. 

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

Yes. The COVID-19 vaccine can be received at the same time as, or at any time before or after non-COVID-19 vaccines. There are two exceptions. COVID-19 vaccines should not be co-administered with the mpox vaccine or adult RSV vaccines.

Can I get the flu shot and the latest COVID-19 vaccine at the same time?

Yes. Individuals six months and older, may receive a COVID-19 vaccine simultaneously with (i.e., same day), or at any time before or after flu vaccines.

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

If you had an allergic reaction within four hours and/or anaphylaxis that happened with a vaccine or injectable medication that does not contain a component or cross-reacting component of the COVID-19 vaccines, you can receive the COVID-19 vaccine as long as you are observed for at least 30 minutes immediately afterwards.

If you're unsure, check with your doctor or health care provider. They will look at your medical records and help you make the decision.

Is it acceptable for someone with food or seasonal allergies to receive the COVID-19 vaccine?

Yes. People with a history of significant allergic reactions and/or anaphylaxis to any food, drug, venom, latex or other allergens not related to the COVID-19 vaccine can get the COVID-19 vaccine followed by observation for at least 15 minutes.

Anyone with allergy issues like allergic rhinitis, asthma and eczema can also receive the vaccine followed by observation for a minimum of 15 minutes.

I had an allergic reaction to a previous dose of the COVID-19 vaccine. Should I get my next dose?

If you had anaphylaxis or a severe or immediate (within one hour) allergic reaction to a previous dose of a COVID-19 vaccine or to any of its components, you should not receive the COVID-19 vaccine in a general vaccine clinic. A referral to an allergist/immunologist is recommended to assess the method for possible (re)administration of a COVID-19 vaccine.

If you had a non-severe allergic reaction which occurred more than one hour after receiving a previous dose of a COVID-19 vaccine or any of its components, an evaluation by an allergist/immunologist may be recommended to confirm you can safely receive the vaccine. 

For individuals with non-severe and delayed reactions to their previous vaccine, vaccination can usually proceed with an extended observation period of at least 30 minutes. 

All Health Unit clinics are staffed with individuals trained to assess and respond appropriately to allergic reactions including anaphylaxis.

Documentation of the consultation with the allergist/immunologist must be provided to the clinic and include:

• a vaccination care plan;
• details/severity of the previous allergic episode(s);
• confirmation that appropriate counselling on the safe administration of vaccine was provided;
• date, the clinician’s name, signature and contact information;
• your name and date of birth.