COVID-19 Vaccine Frequently Asked Questions

Below you will find answers to frequently asked questions about COVID-19 vaccines. These are updated as information becomes available. 

Hamilton Public Health Services acknowledges that some people have experienced legitimate, longstanding, systemic issues that have damaged their trust in the health system. We commit to providing transparent, honest vaccine information to all community membersas it becomes available. We encourage everyone to seek out multiple sources of information from reliable sources to inform your vaccine decisions. 

To ask a health care provider (doctor or nurse) additional questions about COVID-19 vaccines:

About the vaccines

Vaccines teach your immune system how to protect you from diseases. It's much safer for your immune system to learn this through vaccination than by catching the diseases and attempting to treat them.

mRNA technology has been studied for more than 10 years, most often in cancer research and treatment as well as in the development of new vaccines against such infections as pandemic influenza and rabies.  Shortly after COVID-19 was identified scientists were able to map the genes that make up the COVID-19 virus. Once the structure of the genes was known, especially of the spike protein that allows that virus to fuse with and enter our cells, scientists were able to quickly create the vaccine and start the clinical trials that have resulted in the Pfizer and Moderna vaccines that have been approved for use by Health Canada.

Below is an explanation of how the Pfizer-BioNtech and Moderna mRNA COVID-19 vaccines work with your body’s immune response to fight off the COVID-19 virus.

COVID-19 mRNA vaccines tell your body to make "spike proteins" (these cover the outside of the virus and allow it to attach to and enter our cells) specific to virus that causes COVID-19.

  • Your immune system responds to spike proteins by making antibodies that bind to and block the spike protein on the virus’s surface. This is important for protection from disease because the spike protein is what attaches to human cells, allowing the virus to enter. Blocking this entrance prevents infection.
  • Your new antibodies will attack the spike proteins
  • Your new antibodies and immune cells will protect you from illness if you are exposed to COVID-19 virus in the future by remembering how to attack the spike protein

How the different vaccines work

mRNA cannot change your DNA. DNA is contained in the nucleus of our cells. mRNA cannot get into the nucleus or interact with our DNA. mRNA  means ‘messenger RNA’

mRNA is a part of our genetic material that gives instructions to the body, like a recipe. It simply delivers a message.

  • For COVID-19, the mRNA vaccine tells the body to make a harmless “spike protein”. This spike protein is found on the outside of the COVID-19 virus (but is not the virus itself). Our immune system recognizes the spike protein as something that shouldn’t be there and quickly works to attack it by building antibodies and immune cells that will attack the COVID virus if you are exposed in the future.

Human cells break down and get rid of the mRNA soon after they have finished using the instructions. mRNA does not interact with the part of our cells that holds our DNA and cannot be ‘swapped out’ or change the DNA sequence.

The National Advisory Committee on Immunization (NACI) has concluded that those age 12+ can get other vaccines at the same time as the COIVD-19 vaccine. You do not need to wait a certain number of days before or after receiving the COVID-19 vaccine to get another vaccine.

For individuals ages 5 to 11 years old:

  • COVID-19 vaccines should not routinely be given on the same day as other vaccines. At this time, the National Advisory Committee on Immunization (NACI) recommends that children receive the Pfizer-BioNTech COVID-19 vaccine (10 mcg) at least 14 days before or after another vaccine if possible.
  • This is a precaution to help to determine if a side effect that may arise is due to the COVID-19 vaccine or another vaccine, rather than a safety concern.
  • Parents/guardians should consider these recommendations when choosing an appointment date for children’s vaccinations.
  • The minimum waiting period between vaccines is precautionary and there may be circumstances when a dose of a COVID-19 vaccine and another vaccine need to be given at the same time or less than 14 days apart. A healthcare provider can help with this decision

Watch video about getting COVID-19 vaccine at the same time as other vaccines (Black Physicians' Association of Ontario, October 2021)

The duration of protection from the vaccines remains unknown and information will continue to be provided as it is available. A completed two dose COVID-19 vaccine series provides strong protection against COVID-19 and severe outcomes, in the general population. However, two doses may not provide sufficient protection based on suboptimal or waning immune response to vaccines and increased risk of COVID-19 infection. Booster (third) doses can increase immunity and provide further protection. The duration of immunity from contracting the infection also remains unknown. Ongoing monitoring of the COVID-19 vaccines and their  effects on long-term immunity continues.

COVID-19 vaccines are very effective at reducing the risk of severe illness, hospitalization and death and limiting the spread of the virus in a community, but vaccines do not remove all risk of acquiring a COVID-19 infection. Some COVID-19 infections may occur among fully-vaccinated individuals, referred to as ‘breakthrough infection’.

Vaccines work by teaching our immune systems to fight off the virus so that we don’t become severely ill when we come into contact with it, but they cannot prevent us from coming into contact with the virus altogether. The protection a vaccine offers you also depends on the percentage of people around you who are also fully vaccinated, other public health measures you follow, and how much of the virus is circulating. The occurrence of breakthrough infections happens with all vaccines, not just with COVID-19 vaccines.

Your risk of getting COVID-19 and becoming seriously ill or dying is significantly higher if you are not vaccinated, than if you are fully vaccinated. We also know that two doses of a COVID-19 vaccine provide good protection, but three doses are even better.

Remember that it typically takes two weeks after vaccination for the body to build protection (immunity) against the virus that causes COVID-19 and to reach a level to protect us from severe illness. That means it is possible a person could still get COVID-19 before or just after getting a vaccine.  For these reasons, it is important to continue following public health measures even after being vaccinated. This includes staying home if you have any symptoms of COVID-19, wearing a mask indoors, keeping your distance from others, and washing your hands often.

View the number of cases and hospitalizations amongst those who are vaccinated, partially vaccinated and unvaccinated in Hamilton.

Data about the efficacy of vaccines against variants is evolving. The National Advisory Committee on Immunization in Canada will continue to monitor the evidence and update recommendations as needed.

Getting a COVID-19 vaccine will not give you a positive result on a COVID-19 test that is needed for travel. It is possible to test positive on an antibody test. However, these are blood tests and are not commonly used in Ontario.

The National Advisory Committee on Immunization (NACI) has confirmed that a mixed vaccine schedule (receiving both Moderna and Pfizer) can be completed safely and is effective. All vaccines provide strong protection against COVID-19 and its variants. 

For 18 to 29 year olds, it is recommended to receive the Pfizer vaccine as a booster dose if eligible. However,  the Moderna vaccine can still be received with informed consent.

The federal government is working with the World Health Organization and the international community to make sure that individuals who are fully vaccinated in ways that Canadians recognize as safe and effective (mixing of vaccines) are also recognized around the world.

Watch Dr. Matthew Robinson explain about mixing vaccines

Information on mixing vaccine brands English | French

Children who receive the pediatric formulation of the Pfizer-BioNTech COVID-19 vaccine (10 mcg) for their first dose who turn 12 by the time of their second dose may receive the adolescent/adult formulation of the Pfizer-BioNTech COVID-19 vaccine (30 mcg) for their second dose. If a child who has turned 12 by the time of their second dose receives the pediatric formulation (10 mcg), their series should still be considered valid and complete.

The effectiveness of a vaccine depends on the maturity of the immune system rather than body weight. For that reason, there are age-based dosing regimens for all vaccines.

Making a decision about getting vaccinated

Yes. You should still get vaccinated. We do not know the length of immune response in those who have had a COVID-19 infection. When you get the COVID-19 vaccine, it can help protect you against re-infection and may prevent you from transmitting the virus to others.  

Listen to an Ontario doctor explain why you need the vaccine.

Infection with COVID-19 prior to getting 1st or 2nd dose (or completing primary series)
Individuals age 5 and older who had COVID-19 before receiving their first or second COVID-19 vaccine dose, should receive their first or second dose 8 weeks after the start of symptoms, or the date of their positive test if they didn’t have symptoms.

If an individual is 5 years of age and older and is moderately to severely immunocompromised, it is suggested they receive the vaccine 4-8 weeks after the start of symptoms or the date of their positive test if they didn’t have symptoms.

If an individual is 5 years of age and older with a previous history of MIS-C (regardless of immunocompromised statis), it is suggested they receive the vaccine when clinical recovery has been achieved or ≥90 days since the onset of MIS-C, whichever is longer.

You can discuss the timing of doses with your doctor or health care provider. With informed consent, individuals may also receive a COVID-19 vaccine as soon as they do not have symptoms and have completed their isolation after being sick with COVD-19. However, longer intervals between infection and vaccination may result in a better immune response.

Infection with COVID-19 after 2nd dose (or completing primary series) but before first booster dose and/or second booster dose.
Individuals who are eligible for booster dose(s) who have two doses (or completed their primary series) of the vaccine and get COVID-19 are recommended to receive their booster dose(s) 3 months after their symptoms started or 3 months after receiving a positive test result if they didn’t have symptoms.

If they are 12 to 17 years old, at least 6 months (168 days) should have passed after completing their (1st & 2nd dose, or primary series) before receiving their booster dose.

A longer interval between a COVID-19 infection and vaccination is associated with better antibody responses to COVID-19 vaccines. With informed consent, individuals may receive a booster dose once they do not have symptoms and have completed their isolation.

It is always better to prevent an illness, rather than treating it. A vaccine can help stop you from getting ill, decrease the severity of the disease and slow its spread in the community.

Some people have physical and mental health symptoms for weeks or months after having COVID-19. This is sometimes called Long COVID or post COVID-19 condition. It describes a range of symptoms that can last for months after a COVID-19 infection. The most commonly reported symptoms are fatigue, shortness of breath, pain, sleep disturbances, anxiety, and depression. Those who had severe, mild or no symptoms when infected with COVID-19 can get Long COVID.

Although the majority of people who get COVID-19 fully recover, some may not return to their pre-illness levels of health even weeks to months after infection. We do not know why some people have symptoms for weeks or months and others do not. More research is needed.

People with Long COVID-19 may have difficulty functioning the same as they did prior to getting COVID-19, including difficulty performing daily activities such as getting dressed, decreased ability to care for others (such as children), difficulty returning to work and increased health care use. Estimates suggest that 57,000 to 78,000 Ontarians had or are currently experiencing Long COVID.

Vaccination against COVID-19 reduces the likelihood of long COVID by reducing the chance of becoming infected. In addition, vaccination may reduce the likelihood of developing Long COVID among those with post vaccine (“breakthrough”) infections.

(Source: Ontario COVID-19 Science Advisory Table, 2021)

Get informed and make your decisions based on evidence and what makes sense for your family. The Pfizer-BioNtech COVID-19 vaccine is approved for people over 5 years of age and the Moderna COVID-19 vaccine is approved for people over 6 years of age. However, the Ontario government recommends the use of Pfizer-BioNTech vaccine for individuals aged 18-29 years old based on the current available analysis from Ontario’s adverse events following immunization (AEFI) surveillance system. Should individuals aged 18 to 29-year old wish to receive Moderna they can do so with informed consent. The Pfizer vaccine will continue to be used for those ages 5-17. Novavax and J & J/Janssen COVID-19 vaccines are also options for individuals age 18+.

Vaccination is a personal choice that is important for prevention of serious disease. Public Health recommends that everyone who is eligible gets the vaccine once it is available, but recognize that the choice is not always as easy as following this advice. Take the time to read and understand the vaccine information on this page and from other reliable sources.  Follow-up by asking questions and reaching out to trusted medical experts like your family doctor, nurse practitioner, or health care provider.

You can get COVID-19 and spread it to others who might be at higher risk of illness, even if you don’t have symptoms. While some populations such as children and youth typically experience mild symptoms, others can get very sick, require hospitalization and experience more serious and longer-lasting symptoms. In very rare cases, the virus can also cause death.

Check the vaccine distribution page to find out how many people have been vaccinated in Hamilton

Getting a vaccine

Read about where to get your vaccine and other Vaccine Clinic questions

Safety and effectiveness of the COVID-19 vaccine

To date, there are 6 COVID-19 vaccines approved for use in Canada by Health Canada.

  • Pfizer-BioNTech - approved December 9, 2020
  • Moderna – approved December 23, 2020
  • AstraZeneca – approved February 26, 2021
  • Janssen/Johnson & Johnson – approved March 5, 2021
  • Novavax  - approved February 17, 2022
  • Medicago – approved February 24, 2022

Vaccine development and approval

There is a misconception that vaccine research must take a long time. While creating a new vaccine can sometimes take years, the progress on COVID-19 vaccines is happening quickly for many reasons, including:

  • advances in science and technology
  • international collaboration among scientists, health professionals, researchers, industry and governments
  • increased dedicated funding

For any vaccine to reach the general public it must pass careful evaluation by Health Canada and will have to pass safety standards for all age groups it is approved for. What made this vaccine approval feel  faster in comparison to other vaccines is the result of a shared effort by researchers and scientists in every part of the world who combined new processes for review and evaluation of clinical trial data in addition to increased funding for vaccine research.

No corners were cut while creating the vaccines. One minor change to the usual process was put in place: clinical trials were run at the same time as the vaccines were being made/manufactured; that way, vaccines could be shipped out to different countries as soon as the vaccines were approved by the different countries’ health authorities.

Health Canada granted full approval (Notice of Compliance or NOC) for COMIRNATY® (Pfizer-BioNtech ) to prevent COVID-19 in individuals 12 years of age and older in September 2021.

43,448 people were included in the Pfizer trials; 30,000 people were included in the Moderna vaccine trials.

Between 35-40% of the participants were Black or African American, Latinx and Hispanic in both Pfizer and Moderna vaccine clinical trials.
Source: Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. Polack et al. The New England Journal of Medicine

Several hundred people in the trials self-identified as American Indians or Alaska Natives, but this number was too small to be certain how effective the vaccine was in preventing COVID infections in Indigenous people.

43, 783 people from across the United States, Latin America, and South Africa participated in the clinical trials for the Janssen/J&J vaccine. Clinical trials for the Janssen/J&J vaccine included participants from across multiple age ranges and racial groups. Clinical trials for the Janssen/J&J vaccine included the following breakdown of participants: 45.3% Hispanic or Latino, 19.4% Black or African American, 9.5% American Indian or Alaska Native, and 3.3% Asian. 33.5% were aged 60 years and older

Clinical trials make efforts to include a wide range of people to make sure that the evidence would support a wide range of people benefitting from vaccination. 

Clinical trials in children older than 12 years old have begun. Canadian guidelines for COVID-19 vaccines in people who are pregnant, breastfeeding or are immunocompromised can be found here.

All of the approved vaccines have a high efficacy rate against severe disease. In the clinical trials, efficacy against severe disease was shown to be:

  • Pfizer: 75-100% (after dose 2)
  • Moderna: 100% (14 days after dose 2)
  • AstraZeneca: 100% (after dose 2)

Clinical trials showed that beginning 1 week after the second dose, the efficacy of the Pfizer-BioNTech Comirnaty®COVID vaccine against symptomatic COVID-19 was about:

  • 95% effective in protecting trial participants from COVID-19 for those 16 years and older
  • 100% effective for those 12 to 15 years old
  • 90.7% effective for those 5 to 11 years old

Vaccine efficacy is the percentage reduction in disease incidence in a vaccinated group compared to an unvaccinated group under ideal (i.e., clinical trial) conditions (source: WHO). A vaccine with an efficacy of 90% in a trial, for instance, means there was a 90% reduction in cases of disease in the vaccinated group compared to the unvaccinated (or placebo) group.

Real-world studies in adults indicate that mRNA COVID-19 vaccines provide excellent protection against severe disease, including COVID-19 related hospitalization and death following response to the second dose.

Booster doses
Evidence from clinical trials suggests that booster doses of mRNA vaccines given six months after second doses resulted in a good immune response. Real world data suggests that a booster dose provides good short-term effectiveness and safety similar to the second dose of the vaccine. It is unknown at this time how long effectiveness will last.

COVID-19 vaccines are only provided if informed consent is received from the individual and as long as they have the capability to make this decision. This means understanding the treatment, why it is being recommended, and the risks and benefits if they accept or refuse to be vaccinated. If the individual is incapable of consenting to receiving the vaccine, they would need consent from their substitute decision-maker, such as their parent or legal guardian.

The health care provider and family must respect a young person’s decision regarding vaccination. Parents and guardians are encouraged to discuss vaccination with their children prior to attending a clinic. Parents/guardians can choose to accompany their child age 12-17 to get their vaccination but are not required to attend.

Vaccine ingredients

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

Health Canada list of ingredients for all COVID-19 vaccines.

The ingredients in the Pfizer BioNtech COVID-19 vaccine authorized for use in Canada are:

  • Medicinal ingredient
    • mRNA
  • Non-medicinal ingredients
    • ALC-0315 = ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate)
    • ALC-0159 = 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide
    • 1,2-Distearoyl-sn-glycero-3-phosphocholine
    • cholesterol
    • dibasic sodium phosphate dihydrate
    • monobasic potassium phosphate
    • potassium chloride
    • sodium chloride
    • sucrose
    • water for injection
  • Non-medicinal ingredients (age 5-11)
    • ALC-0315 = ((4-hydroxybutyl) azanediyl)bis (hexane-6,1-diyl)bis(2-hexyldecanoate)
    • ALC-0159 = 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide
    • 1,2-distearoyl-sn-glycero-3-phosphocholine
    • cholesterol
    • sodium chloride
    • sucrose
    • tromethamine
    • tromethamine hydrochloride
    • water for injection

Recommendations for people with serious allergies

The ingredients in the Moderna COVID-19 vaccine authorized for use in Canada are:

  • Medicinal ingredient
    • mRNA
  • Non-medicinal ingredients
    • 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)
    • acetic acid
    • cholesterol
    • lipid SM-102
    • polyethylene glycol (PEG) 2000 DMG
    • sodium acetate
    • sucrose
    • tromethamine
    • tromethamine hydrochloride
    • water for injection

Note: Polyethylene glycol (PEG) is in both mRNA vaccines. It can also be found in laxatives, makeup, skin care products, personal lubricants, toothpastes, and some contact lenses. It is also in cough syrup, and in some food and drinks.

There are no pork-derived materials, the fatty layers that protect the mRNA are plant-based or synthetic, and there are no blood fractions or fetal cells products in the vaccines.

Source: South Asian COVID Task Force Canada.

No, the vaccine does not contain a “microchip”. This concern started after comments made by Bill Gates from The Gates Foundation about a digital certificate of vaccine records. A digital certificate is not something that can be contained with in a vaccine and is not a microchip. The technology referred to by Gates has nothing to do with the development, testing or distribution of the COVID-19 vaccine.

Vaccine side effects

After being vaccinated, it's common to have mild side effects. This is the body's natural response, as it's working hard to build immunity against the disease. This is known as the inflammatory response or reaction. Side effects will likely be moderate and resolve after a few days.

Common side effects that have been reported in the clinical trials for the Pfizer BioNtech COVID-19 vaccine include:

very common ≥10%
(more than 1 in 10 doses)
common  1%-10%
(1 in 100 to 1 in 10 doses)
uncommon 1%
(1 in 100 doses)
  • pain at the injection site
  • headache
  • feeling tired
  • muscle or joint pain
  • fever or chills
  • redness & swelling at the injection site
  • joint pain (very common after 2nd dose)
  • diarrhea
  • nausea and/or vomiting (common after 2nd dose for adults)
  • enlarged lymph nodes

Please see the product monograph for a complete list of reported side effects.

These effects are more likely after the second dose of vaccine and will typically go away in a day or two. These effects are a normal part of your body’s response to most vaccines – it is a sign that your body’s immune system is learning how to recognize and fight the virus that causes COVID-19. Some people may experience more serious allergic reactions to the vaccine, but these are unlikely and tracked closely by Health Canada as part of on-going monitoring of vaccine safety.

If you have questions about these effects, reach out your health care provider (doctor, nurse or pharmacist).

In rare cases, serious allergic reactions (anaphylaxis) can occur. Allergic reactions can be treated and are usually temporary. Seek medical attention if you have trouble breathing, have hives or swelling of the face and throat. 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. See below for reporting side effects.

The pediatric Pfizer-BioNTech COVID-19 vaccine, like medicines and other vaccines, may cause side effects. In clinical trials, most of the side effects experienced were mild to moderate, and usually resolved within a few days. See the product monograph for a complete list of reported side effects.

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

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

  • pain, swelling and redness at the injection site
  • headache
  • feeling tired
  • muscle pain
  • fever
  • chills
  • vomiting
  • diarrhea
  • joint pain

The Moderna COVID-19 vaccine, like medicines and other vaccines can cause side effects. In clinical trials, most of the side effects experienced were mild to moderate and on average did not last longer than three days. See the product monograph for a complete list of reported side effects.

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

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

uncommon 1%
(1 in 100 doses)

  • pain at the injection site
  • lymphadenopathy (enlarged lymph nodes)
  • headache
  • feeling tired
  • muscle or joint pain
  • chills
  • redness & swelling at the injection site (very common after 2nd dose)
  • nausea and/or vomiting (very common after 2nd dose)
  • fever (very common after 2nd dose)

Side effects for J & J vaccine

Side effects for Novavax vaccine

Expected side effects (Pfizer & Moderna) (Janssen/J & J) (Novavax)

Some people may experience mild COVID-19  infection, but it can also cause some people to become very sick or even lead to death. There is some research to show that even a mild case of COVID-19 can be harmful to a person’s lungs (which makes breathing hard) and to their heart and cardiovascular system (your heart and how blood flows through your body). There is also a number of people experiencing on-going and at times debilitating symptoms for weeks or months after their initial COVID-19 infection (called ‘Long COVID’).

Your risk of dying from COVID-19 increases as you age, if you are male or if you have chronic health conditions such as heart or lung disease or diabetes.

As part of the vaccine safety program in Canada, ongoing monitoring of the COVID-19 vaccines will continue. Very careful tracking of side effects for those who are vaccinated is carried out at local, provincial and national levels. There is also longer-term follow-up of clinical trial participants. Health Canada posts weekly reports on vaccine safety.

Rare cases of myocarditis and pericarditis have been reported after mRNA COVID-19 vaccination (Pfizer-BioNTech and Moderna) in Canada and internationally, including in the United States and Israel.  Myocarditis is inflammation of the heart muscle, and pericarditis is inflammation of the lining outside the heart. In both cases, the body’s immune system is causing inflammation in response to an infection or some other trigger. Symptoms can include chest pain, shortness of breath, or palpitations. Available information indicates that tThese illnessesse cases have occurred: mainly in adolescents and young adults, more often in males than females, more commonly after the second dose, and typically within several days after vaccination. Most cases appear to be mild and respond well to conservative treatment (e.g. non-steroidal anti-inflammatory drugs) and rest.

The Ontario government recommends the use of Pfizer-BioNTech vaccine for individuals aged 18-29 years old based on the current available analysis from Ontario’s adverse events following immunization (AEFI) surveillance system due to an observed increase in Ontario of the very rare heart condition called pericarditis/myocarditis following vaccination with Moderna compared to Pfizer in the 18 to 29 year old age group, particularly among males. The majority of reported cases of myocarditis/pericarditis 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. However, sShould individuals aged 18 to 29-years old wish to receive Moderna they can continue to do so with informed consent. The province will continue using the The Pfizer vaccine will continue to be used for youth ages 5 to 17. No cases of myocarditis/pericarditis were reported in Pfizer clinical trials for those age 5 to 11 (Source: FDA, 2021).

As a precaution, children who experience myocarditis and/or pericarditis after a first dose of the vaccine should wait to get a second dose until more information is available. Children who have a history of myocarditis unrelated to COVID-19 vaccination should consult their clinical care team for individual considerations and recommendations. If they are no longer under active care for myocarditis, they may receive the vaccine.

The rate of myocarditis and pericarditis following a booster dose of a COVID-19 mRNA vaccine is currently unknown.

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.

Watch Dr. Ainsworth (Hamilton Health Sciences) speak about myocarditis and vaccines


The product information for the Pfizer-BioNTech COVID-19 vaccine to describe very rare reports of Bell’s Palsy following vaccination. Cases have been reported in a small number of people in Canada and internationally.

The Moderna COVID-19 vaccine label contains safety information about reported cases of Bell’s Palsy following vaccination.

Health Canada is continuing to monitor side effects for all authorized COVID-19 vaccines in Canada.

Bell's Palsy is typically a temporary facial muscle weakness or paralysis. Symptoms appear suddenly and generally start to improve after a few weeks. The exact cause of Bell’s Palsy is unknown but it is believed to be the result of swelling and inflammation of the nerve that controls muscles on one side of your face.

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 vaccines will not give you a COVID-19 infection. None of the approved vaccines contains a live version of the COVID-19 virus. Instead all the vaccines either deliver, or cause our bodies to make, harmless spike proteins only found on the surface of the COVID-19 virus and teaches your body how to spot and respond to this protein so when the real virus comes along, the body can fight it off.

Severe reactions are uncommon but if you need immediate medical assistance, call 911.

View our fact sheet for a list of common, expected side effects and uncommon side effects that may need to be reported as adverse reactions (PDF, 135 KB)

Discuss any of the uncommon reactions with your family doctor. If you don’t have a family doctor, a walk-in clinic might be preferred. A doctor can diagnose these uncommon reactions and report them to public health. If you do not have access to a doctor, please call Hamilton Public Health Services Vaccine program at 905-546-2424 ext. 7556 to report symptoms.

Access the Adverse Events reporting form

Considerations for those with health conditions

Some individuals may consider themselves more vulnerable to side effects or negative effects from the vaccine. Speak with your doctor or health care provider about any questions or concerns you have about COVID-19 vaccines.

The following are recommendations from the Ontario Ministry of Health: COVID-19 Vaccine Administration

It is recommended that all moderately to severely immunocompromised individuals receive a 3-dose primary series of COVID-19 vaccine. These individuals are encouraged to speak with their treating health care provider regarding the timing of vaccination in relation to therapy for their underlying health condition and/or treatment modification in view of possible decreased vaccine effectiveness with the use of immunosuppressive therapy. See the COVID-19 Vaccine: Canadian Immunization Guide’s section on immunocompromised persons and the COVID-19 Vaccine and Booster Dose Recommendations for more information.

It is recommended that re-vaccination with a new COVID-19 vaccine primary series be initiated post-transplantation for hematopoietic stem cell transplant (HSCT), hematopoietic cell transplants (HCT) (autologous or allogeneic), and recipients of CAR-T-cell therapy given the loss of immunity following therapy or transplant. Optimal timing for re-immunization should be determined on a case-by-case basis in consultation with the clinical team. For additional information on organ transplantation, consult the Canadian Society of Transplantation statement on COVID-19 vaccination.

This information is from the Ontario Ministry of Health: COVID-19 Vaccination Administration

Individuals with known allergies to components of the vaccines may speak with an appropriate physician or Nurse Practitioner for evaluation. This assessment will enable the development of a vaccination care plan which may include receiving the vaccine under the supervision of your physician.

Documentation of the discussion with the physician/NP may be provided to the clinic and can include a vaccination care plan (including what types of parameters the clinic should meet to provide safe vaccination administration, such as availability of advanced medical care to manage anaphylaxis), details/severity of the previous allergic episode(s), confirm that appropriate counselling on the safe administration of vaccine was provided, and include the date, the clinician’s name, signature and contact information as well as the individual’s name and date of birth.

COVID-19 vaccines do not cause male or female infertility. There is no scientific reason that the COVID-19 vaccines would impact fertility for those people trying to get pregnant. No loss of fertility has been reported among trial participants or among the millions who have received the vaccines to date, and no signs of infertility appeared in animal studies. Recent research showed that there were no differences in the numbers of conceptions in the vaccine trials between participants who got the vaccine and those who got the placebo. Studies show that pregnant women are more likely to be hospitalized when they have COVID-19, but they are not more likely to miscarry.

If you are considering or undergoing IVF or fertility treatments, speak with your health care provider about vaccination.  (Source:


All pregnant and breastfeeding individuals are elgible and should receive all recommended doses of a COVID-19 vaccine (including booster doses) as soon as possible, at any stage in pregnancy, as COVID-19 infection during pregnancy can be severe.

  • COVID-19 infection in pregnancy increases the risk of medical complications and death.
  • Pregnant women who contract COVID-19 are:
    • Five times more likely to be hospitalized and spend 3.73 days longer in hospital
    • 10 times more likely to be admitted to the intensive care unit (ICU)
    • More likely to suffer from severe illness
    • More likely to require ventilation/life support breathing

(Source: Munshi L, Wright JK, Zipursky J, et al. The incidence, severity, and management of COVID-19 in critically ill pregnant individuals. Science Briefs of the Ontario COVID-19 Science Advisory Table.)

  • After the COVID-19 infection has resolved, many pregnant women will continue to experience ongoing medical complications.
  • COVID-19 infection in pregnancy significantly increases the risk of stillbirth, premature birth, high blood pressure, caesarean delivery and low birth weight.
  • There is also an increased risk that the baby will need to be admitted to neonatal intensive care.
  • There is no evidence to suggest that taking the COVID-19 vaccine will impact your pregnancy.
    • Several studies with more than 17,000 pregnant women have shown that vaccination immediately prior to and/or during pregnancy has no impact on pregnancy outcomes (i.e. no change in the rate of miscarriage, premature birth, stillbirth, growth restriction, high blood pressure during pregnancy, medical complications of pregnancy or maternal death).
    • A study of more than 35,000 pregnant and/or breastfeeding women who were monitored at the time of COVID-19 vaccination found no difference in the rate of side effects compared with non-pregnant individuals.
    • Real-world safety data is now available for hundreds of thousands of pregnancy individuals who have received the COVID-19 vaccine.
  • The antibodies you make to fight COVID-19 following vaccination also pass to your baby, which may keep them safe after birth.
  • The COVID-19 vaccine does NOT contain any live virus, any mercury, aluminum, formaldehyde or any substances harmful to you and/or baby, any human and/or animal blood or by product(s).
  • Getting vaccinated before getting pregnant will protect you and your future baby from the increased risks association with COVID-19 infections in pregnancy.

It is recommended, but not required, that pregnant individuals have discussion with their treating health care provider, or with a health care provider familiar with their pregnancy, that includes:

  1. a review of the potential risks and benefits of the vaccine,
  2. a review of the risk of acquiring a COVID-19 infection during pregnancy,
  3. a review of the potential risks /consequences associated with a COVID-19 infection during pregnancy, and
  4. an acknowledgment of the limited evidence from clinical trials of COVID-19 vaccines in the pregnant population.  

For additional information on COVID-19 vaccination in pregnancy:

All breastfeeding individuals are eligible and should receive all recommended doses of a COVID-19 vaccine (including booster doses) as soon as possible.

  • Vaccines protect you from COVID-19 infection and help prevent you from passing it to your baby or other family members.
  • You can continue breastfeeding after getting vaccinated; the vaccine is not detectable in breast milk.
  • Antibodies have been shown to pass in the breastmilk after maternal vaccination and may protect your baby against COVID-19.
  • Studies show that receiving a COVID-19 vaccine while breastfeeding does not disrupt your breastfeeding and does not have an adverse impact on your baby.


People who menstruate (get a period) do not need to schedule their COVID-19 vaccine around their menstrual cycle. There are no issues with getting the vaccine during your period.

Delaying your vaccine around your cycle may leave you unprotected from COVID-19 for a longer time without providing any known benefit.

Menstruation can be influenced by many things, such as environmental changes, stress, sleep and some medications. When your immune system is working hard because you’re vaccinated or sick, you may experience changes in how the lining (endometrium) of the uterus responds so it is possible to see some changes in menstruation.

Researchers are confident that the vaccine is safe, and that there is not enough data to suggest that there should be concerns over potential changes to the menstrual cycle.

The good news is that any changes you experience in your menstrual cycle after getting the vaccine are temporary, so it shouldn’t be a reason not to get a shot. However, people with concerns should speak with their doctor since cycles can be delayed for other reasons as well.

Source: Immunize BC

Vaccine information for diverse communities

City of Hamilton Public Health Services has Vaccine Ambassadors from diverse communities who are doing community outreach activities and education about COVID-19 vaccinations. Please contact [email protected].

Parents in Hamilton talk about making the decision to get their children vaccinated to protect them and their loved ones against COVID-19.



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