COVID-19: Effectiveness and benefits of vaccination

On this page

• Effectiveness of vaccination
• Recommended doses
• Follow public health measures
• Monitoring

Effectiveness of vaccination

Vaccination is one of the most effective ways to protect our families, communities and ourselves against COVID-19. Evidence indicates that the vaccines used in Canada are very effective at preventing severe illness, hospitalization and death from COVID-19.

A booster dose following a primary series of mRNA vaccines offers better protection against Omicron infection and severe disease than the primary series alone.

Among people who are vaccinated against COVID-19, studies show that:

• their level of protection against infection from the primary series decreases over time and is low against Omicron, but can be improved with a booster dose
• the primary series appears to maintain good protection against severe disease and hospitalization caused by Omicron
• protection against severe disease and hospitalization is higher after a booster dose

Vaccination is very important, even if you've been previously infected with COVID-19. While infection alone provides some protection, vaccination after infection helps improve the immune response and may provide better and longer-lasting protection.

Risk factors for exposure to and severe outcomes from the virus should be assessed when considering the timing of COVID-19 vaccination. Consult your local public health authority for more information on when you should get vaccinated after having COVID-19.

We continue to closely monitor the evolving science and research related to vaccine effectiveness.

Learn more about:

• COVID-19: Contact your provincial or territorial public health authority
• COVID-19: Definition of primary series
• Vaccines for COVID-19: Booster doses
• COVID-19 variants of concern

Recommended doses

For best protection against COVID-19, it's important to stay up to date with recommended COVID-19 vaccinations .

A primary series consists of either of the following:

• 2-dose series of any combination of the following vaccines:
  • Pfizer-BioNTech Comirnaty
  • Moderna Spikevax
  • Medicago Covifenz
  • Novavax Nuvaxovid
  • AstraZeneca Vaxzevria
• a single-dose Janssen (Johnson & Johnson) vaccine

The National Advisory Committee on Immunization (NACI) recommends an 8-week interval between your first and second dose. This results in better protection than with a shorter time between doses.

Booster doses

People 18 years of age and over are recommended to get a booster dose. NACI recommends that this booster dose be given at least 6 months after completion of the primary series.

Additional booster doses are recommended for certain groups. Consult your local public health authority for more information on what doses are recommended for you at this time.

Receiving all your recommended doses provides:

• very good protection against severe illness, hospitalization and death
• some protection against getting infected and becoming sick
  • this protection may decrease over time and isn't as effective for Omicron as it was with other variants

Learn more about:

• Vaccines for COVID-19: Booster doses
• COVID-19: Contact your provincial or territorial public health authority
• Vaccines for COVID-19: Who is eligible
• COVID-19 variants of concern

Follow public health measures

Individual public health measures are effective actions you can take everyday to help reduce the spread of COVID-19. It’s most effective to use several measures together and alongside vaccination. If you develop symptoms or test positive for COVID-19:

• stay home and isolate yourself away from others and
• follow the advice of your local public health authority on testing and isolation requirements

Contact your health care provider if you have specific questions or concerns about your health.

Learn more about:

• COVID-19: Individual public health measures
• COVID-19 mask use: Advice for community settings
• COVID-19: Improving indoor ventilation
• COVID-19: Symptoms and treatment
• COVID-19: How to quarantine or isolate at home
• COVID-19: Contact your public health authority

Monitoring

Ongoing monitoring in Canada and around the world helps determine whether changes to the virus affect:

• transmission
• disease severity
• effectiveness of vaccines
• effectiveness of drug treatments
• ability of testing to detect the virus

Learn more about:

• Vaccines and treatments for COVID-19: Monitoring COVID-19 variants