AstraZeneca COVID-19 vaccine: What you should know
Many potential drugs and vaccines for use against COVID-19 are being evaluated in Canada and around the world. We’re closely tracking all potential drugs and vaccines in development.
You can search the complete list of applications received for COVID-19-related drugs and vaccines and their status.
On this page
- About the AstraZeneca COVID-19 vaccine
- How it works
- How it’s given
- Possible side effects
- Vaccine safety after authorization
About the AstraZeneca COVID-19 vaccine
The AstraZeneca COVID-19 vaccine (ChAdOx1-S) is used to prevent COVID-19. This disease is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Canada has authorized 2 manufacturers of the ChAdOx1-S vaccine:
- AstraZeneca (brand name AstraZeneca COVID-19 Vaccine)
- Verity Pharmaceuticals and Serum Institute of India (SII) in collaboration with AstraZeneca (brand name COVISHIELD Vaccine)
AstraZeneca COVID‐19 Vaccine (manufactured by AstraZeneca) and COVISHIELD (manufactured by Serum Institute of India) are ChAdOx1-S recombinant vaccines developed by AstraZeneca and Oxford University. Health Canada has reviewed the manufacturing information for these vaccines and found them to be comparable.
The vaccine is approved for people who are 18 years of age and older. Its safety and effectiveness in people younger than 18 years of age have not yet been established.
Health Canada authorized both applications for this vaccine with conditions on February 26, 2021, under the interim order respecting the importation, sale and advertising of drugs for use in relation to COVID-19.
Find detailed technical information about the AstraZeneca vaccine, such as the product monograph and our regulatory decision summary, in the COVID-19 vaccines and treatments regulatory portal.
- Medicinal ingredient
- Adenovirus vector vaccine
- Non-medicinal ingredients
- disodium edetate dihydrate (EDTA)
- L-histidine hydrochloride monohydrate
- magnesium chloride hexahydrate
- polysorbate 80
- sodium chloride
- water for injection
How it works
Viral vector-based vaccines use a harmless virus, such as an adenovirus, as a delivery system. This “vector” virus is not the virus that causes COVID-19. Adenoviruses are among the viruses that can cause the common cold. There are many different types of adenoviruses, and many have been used as delivery systems for other vector-based vaccines for decades.
When a person is given the vaccine, the vector virus contained within the vaccine produces the SARS-CoV-2 spike protein. This protein is found on the surface of the virus that causes COVID-19. This protein will not make you sick. It does its job and goes away.
Through this process, the body is able to build a strong immune response against the spike protein without exposing you to the virus that causes COVID-19.
How it’s given
The vaccine is given by 2 separate injections of 0.5 mL each into the muscle of the arm. For the vaccine to work best, you need to get 2 doses: a first dose and then a second dose 4 to 12 weeks later.
Immunity develops over time. It takes about 2 weeks to develop significant protection against COVID-19. For the greatest protection, you will need the second dose.
The AstraZeneca COVID-19 vaccine showed an effectiveness of about 62% in preventing symptomatic COVID-19 disease beginning 2 weeks after the second dose. This effectiveness rate is based on an analysis of results from participants who had received the 2 dose regimen that will be used in Canada.
Possible side effects
In general, the side effects observed during the clinical trials are similar to what you might have with other vaccines.
The side effects that followed vaccine administration in clinical trials were mild or moderate. They included things like pain at the site of injection, body chills, feeling tired and feeling feverish.
These are common side effects of vaccines and do not pose a risk to health.
As with all vaccines, there’s a chance that there will be a serious side effect, but these are rare. A serious side effect might be something like an allergic reaction. Speak with your health professional about any serious allergies or other health conditions you may have before you receive this vaccine. Very rare cases of blood clots with low platelets have been reported. Learn more about this rare possible side effect.
Vaccine safety after authorization
As for all medicines, Health Canada will continue to monitor the safety of the AstraZeneca COVID-19 vaccine in Canada closely. Along with the Public Health Agency of Canada and working in close collaboration with the provinces and territories and the manufacturer, we will monitor for any adverse events that may develop after immunization.
Once the product is on the market, the manufacturers (AstraZeneca Canada Inc. and Verity Pharmaceuticals/Serum Institute of India (SII)) are legally required to submit reports of adverse events to Health Canada.
The manufacturer is planning to follow clinical trial participants for at least 1 year after the second dose of the vaccine is given. It must communicate any safety concerns to Health Canada.
To ensure that the benefits of the vaccine continue to outweigh the risks, we may also impose terms and conditions at any time. For example, we can require the manufacturer to take further risk mitigation measures. We can also ask the manufacturer to submit additional safety information.
Health Canada will continue to review all the available safety data as it becomes available. We will take appropriate action, if required, to protect the health and safety of Canadians.
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