COVID-19: Effectiveness and benefits of vaccination
On this page
- Health benefits of vaccination
- Becoming fully vaccinated
- Variants of concern
- Proof of vaccination in Canada
Health benefits of vaccination
Vaccination is one of the most effective ways to protect our families, communities and ourselves against COVID-19.
Evidence indicates that vaccines are very effective at preventing severe illness, hospitalization and death from COVID-19, including against Alpha and Delta variants of concern. However, there’s a small percentage of the population who are vaccinated that will still be infected with COVID-19 if they’re exposed to the virus.
mRNA vaccines
Evidence indicates that people who are fully vaccinated with an mRNA vaccine (Pfizer-BioNTech Comirnaty and Moderna Spikevax) are less likely to:
- have COVID-19 with or without symptoms
- spread COVID-19 to others
Viral vector vaccines
People who have been fully vaccinated with a viral vector vaccine (AstraZeneca Vaxzevria) are less likely to:
- have COVID-19 with symptoms
- spread COVID-19 to others
Long-term symptoms
Vaccination is also the best prevention against post COVID-19 condition. This condition refers to symptoms some individuals experience for weeks or months after being infected with COVID-19. Symptoms can be very different from those during the initial infection.
The condition can affect both adults and children.
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Becoming fully vaccinated
In general, people are considered fully vaccinated:
- 2 weeks after their second dose in a 2-dose series, such as the Pfizer-BioNTech Comirnaty or Moderna Spikevax vaccines or
- 2 weeks after a single-dose vaccine, such as Johnson & Johnson's Janssen vaccine
If you have received 1 dose of a 2-dose series, you're considered partially vaccinated.
Completing your vaccine series is important. Current evidence shows it takes:
- 2 weeks or more after the first dose to provide good protection
- up to 2 weeks after the second dose to provide higher protection
The effectiveness of a 2-dose vaccine series increases after the second dose. That's why it's important to return at the time advised by your local health authority for longer-lasting protection.
You’ll have very good protection against infection, including against most current variants of concern. However, as vaccines are rarely 100% effective, a small number of fully vaccinated people may become infected with or without symptoms. As a result, you may still be asked to get a COVID-19 test.
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Variants of concern
Viruses change over time. While most changes aren't significant, some can create new variants of concern.
Having as many people vaccinated as possible may also reduce the risk of:
- ongoing circulation of the virus
- the appearance of future variants
Current evidence suggests that COVID-19 vaccines in Canada are effective at providing protection against the known variants of concern at this time.
Ongoing surveillance in Canada and around the world will help determine whether changes to the virus affect:
- transmission
- disease severity
- effectiveness of vaccines
- drug treatments
- testing
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Proof of vaccination in Canada
Some provinces or territories may choose to put in place local public health measures that are based on a person’s COVID-19 vaccination status. You may be asked to provide the documentation you received after your vaccination. This may be in the form of a vaccination receipt (either physical or digital) or a verifiable vaccination credential.
Similarly, these documents may be requested for international travel.
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