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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. Health Canada has approved four COVID-19 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, MERS-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 more information on COVID-19 vaccines and ingredients, see the Ministry of Health COVID-19 Vaccine Information Sheet.

Information about COVID-19 Vaccine Safety:

Side Effects & Adverse Events

The Ministry of Health's COVID-19 Vaccine Information Sheet describes possible side effects and next steps if you are experience side effects that are worrying you. For information about what you should expect after your COVID-19 vaccine, please review the Ministry of Health’s After Your COVID-19 Vaccine guidance.

For more information about the reported side effects or reactions following COVID-19 vaccinations, visit Health Canada’s website

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 at least 28 days before receiving another vaccine.
  • Individuals who are NOT in the vaccine authorized age group.

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.

If you received a first dose of an mRNA vaccine, you can safely receive either of the mRNA vaccines as your second dose. If you received a first dose of AstraZeneca, you can safely receive AstraZeneca or an mRNA vaccine as your second dose. 

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.


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

Vaccination HandoutFR

Needle Fears Resource

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

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Last modified: 
Thursday, September 2, 2021 - 3:34pm