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Testing and Health Canada Approval

Vaccination is one of the most effective ways to prevent the spread and reduce the impact of infectious diseases. Before any vaccines are available for use in Ontario or Canada, they undergo large clinical trials to determine if they are safe and effective. A list of authorized clinical trials is available on Health Canada’s website. Health Canada has maintained the same scientific and quality standards for the review and approval of COVID-19 vaccines that were in place before the pandemic. As of March 5, 2021, Health Canada has approved four vaccines. Having a variety of approved COVID-19 vaccines allows for a more flexible response to the pandemic to protect communities more quickly.

COVID-19 vaccines are being developed quickly, are they still safe?

Only vaccines that Health Canada determines to be safe and effective will be approved for use in Canada and Ontario. The progress on COVID-19 vaccines happened quickly for many reasons including:

  • Research on other strains of coronavirus before COVID-19 (e.g. Sars-CoV) 

  • Advances in science and technology
  • International collaboration among scientists, health professionals, researchers, industry and governments
  • Increased dedicated funding

As vaccines for COVID-19 are approved and administered, Health Canada will continue to oversee their safety through a vaccine monitoring system.

The National Advisory Committee on Immunization (NACI) provides regularly updated recommendations on the use of COVID-19 vaccines, and information on efficacy and effectiveness, storage requirements, vaccine safety and adverse events following immunization, and more.

For COVID-19 vaccine ingredients, see product monographs:


COVID-19 vaccine resources supporting individuals with developmental disabilities, families and caregivers by Connectability

First Nations, Inuit and Métis perspectives and knowledge sharing on COVID-19 vaccines by Women’s College Hospital, Maad'ookiing Mshkiki – Sharing Medicine

Easy read vaccine aftercare infographics by Health Design Studio – Available in multiple languages

Dr. Onye Nnorom talks about her thoughts on the COVID-19 vaccine by the Black Health Alliance

Information about COVID-19 Vaccine Safety:

Side Effects

Ongoing research on the COVID-19 vaccines indicates serious side effects are extremely rare. Similar to other vaccines, individuals can develop mild side effects  after receiving the vaccine, and therefore you will be asked to wait for 15 minutes to ensure you are feeling well. Experiencing one or more of the following side effects can be expected and indicates that the vaccine is working to produce protection or immunity:

  • Pain where the needle was given
  • Redness and swelling where the needle was given
  • Tiredness
  • Headache
  • Muscle pain
  • Joint pain
  • Chills
  • Mild fever
  • Swollen glands (uncommon)

If you are concerned about any side effect after you receive the vaccine, contact your health care provider to determine next steps. Health Canada continues to monitor the safety and effectiveness of COVID-19 vaccines even after authorization and regularly shares updates on their website. For more information about the reported side effects or reactions following COVID-19 vaccinations, visit Health Canada’s website

The AstraZeneca COVID-19 vaccine is associated with a very rare side effect known as Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT). If you develop any of the following symptoms after receiving the vaccine, please seek immediate medical attention:

  • Shortness of breath
  • Pain in chest
  • Swelling or coldness in an arm or leg
  • Persistent abdominal pain
  • Severe or worsening headaches or blurred vision
  • Multiple small bruises, red or purple spots or blood blisters under the skin

COVID-19 Vaccination After Care

Adverse Events

An adverse event following immunization (AEFI) is an unwanted or unexpected health effect that happens after an individual is vaccinated. Adverse events may or may not be caused by the vaccine. If you or someone in your household is experiencing an adverse event following immunization, please contact your health care provider for medical advice or call 911 for a medical emergency. Some adverse events or reactions include:

  • Hives
  • Swelling of the face or mouth
  • Trouble breathing/chest pain
  • Very pale colour and serious drowsiness
  • High fever (over 40°C)
  • Convulsions or seizures
  • Other serious symptoms

Please view Public Health Ontario’s information on Myocarditis and Pericarditis (inflammation of the heart muscle) following COVID-19 mRNA vaccines.

If you experience an adverse event following immunization, please report it to your health care provider. To learn more about adverse events and how to report them, visit Public Health Ontario’s Adverse Event Following Immunization Info Sheet.

Recommendations for the Use of COVID-19 Vaccines

The National Advisory Committee on Immunization (NACI) recommends that the COVID-19 vaccine should not be offered to the following individuals until further evidence is available:

  • Individuals who have any symptoms that could be due to COVID-19 or have tested positive for COVID-19 and have not fully recovered.
  • Individuals who are required to self-isolate should not leave during their isolation period to receive a COVID-19 vaccine.
  • Individuals who have received another vaccine (not a COVID-19 vaccine) in the past 14 days.
  • Individuals who intend to receive another vaccine (not a COVID-19 vaccine) within 4 weeks of receiving the COVID-19 vaccine.
    • Anyone who received a dose of COVID-19 vaccine should wait 28 days before receiving another vaccine.
  • Individuals who are NOT in the authorized age group.
    • The Pfizer-BioNTech vaccine: Individuals under the age of 12 years.
    • The Moderna vaccine: Individuals under the age of 18 years.
    • The AstraZeneca vaccine: Individuals under the age of 18 years.
    • The Janssen (Johnson & Johnson) vaccine: Individuals under the age of 18 years.

As further information becomes available from clinical trials and Health Canada approvals, the groups for which the vaccines are authorized for use could change.

Individuals who have experienced major venous and/or arterial thrombosis (blood clot) with thrombocytopenia (low platelets) following vaccination with any vaccine, or who have experienced a previous cerebral venous sinus thrombosis (CVST) with thrombocytopenia or have experienced heparin-induced thrombocytopenia (HIT) cannot receive the AstraZeneca COVID-19 Vaccine. For more information on the use of COVID-19 vaccines, please view the Ministry of Health COVID-19 Vaccine Information Sheet.

Can you get the vaccine with your pre-existing condition?

It is recommended to speak with your health care provider before you receive the vaccine if you have any pre-existing health conditions or concerns.

Guidance for special populations, including breastfeeding women, individuals with autoimmune conditions and immunocompromised persons, and individuals with allergies is available in the Vaccination Recommendations for Special Populations guidance document.

Pregnant individuals may choose to receive the vaccine at any time during their pregnancy. It is recommended that pregnant individuals have a discussion prior to being vaccinated with their treating health care provider or with a health care provider familiar with their pregnancy. Please see the COVID-19 Vaccination Recommendations for Special Populations for further details on COVID-19 vaccination for pregnant individuals. In addition, view Vaccination in Pregnancy & Breastfeeding Decision-Making Support Tool.

Please note:  The Windsor-Essex County Health Unit (WECHU) does not provide individual patient counselling on the suitability of receiving the COVID-19 vaccine. Individuals should speak to their health care provider about any serious allergies or other health concerns they may have before receiving the vaccine.

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Last modified: 
Thursday, June 17, 2021 - 11:46am