About COVID-19 Vaccines

The following information was developed for this website by medical professionals and public health experts using Canadian government and other scientific and medical sources. It is not intended as medical advice. Always seek the advice of a qualified healthcare provider with any questions you may have regarding the COVID-19 vaccine.

Last revision: 2021-08-13

Vaccination against the COVID-19 virus will help protect you from getting sick or dying with COVID-19. Also, to stop the spread of COVID-19 in Canada, sufficient numbers of Canadians need to be vaccinated to stop community transmission of the virus.

Even if a person does not die of COVID-19, they may have long- term complications including memory loss, fatigue, unexplained breathing difficulties, and damage to the lungs and heart.

If enough people have immunity, the virus is less likely to spread. We need to vaccinate at least 85-90% of the eligible population to achieve herd immunity and go back to our daily lives, keep businesses open, and continue to see and hug our loved ones.

No, all COVID-19 vaccines are free.

If you received an mRNA vaccine (Pfizer BioNTech or Moderna) as your first dose, you will be offered an mRNA vaccine as your second dose. It is preferred that you receive the same type of vaccine as you had the first time, unless it’s not readily available or unknown, in which case it’s ok to receive the other type of mRNA vaccine. Both are equally safe and effective.

An mRNA vaccine is preferred as the second dose for individuals who received a first dose of the AstraZeneca, based on evidence of a potentially better immune response and strong safety profile from this mixed vaccine schedule. 

All vaccines approved for use in Canada effectively reduce hospitalization and serious illness, and all are almost 100% effective in preventing death from COVID-19.

The important point is that you shouldn’t wait to get vaccinated with two doses for full protection. New virus variants are emerging that are causing more cases, hospitalizations and deaths, and mass vaccination is the only way to stop this.

Based on clinical trials involving tens of thousands of vaccine recipients, the vaccines authorized in Canada have been very effective against symptomatic disease, severe illness, hospitalization and death. 

Although some of the new variants can create occasional breakthrough infections in fully vaccinated individuals, these illnesses are usually quite mild and often without any symptoms at all.

Vaccine resistance is more like a sliding scale than a switch. Our immune systems can continue to recognize and respond against spike proteins even of mutated forms of the virus. And our immune responses evolve, typically growing stronger and more effective over the course of an infection. So even if you’re exposed to a partially-resistant variant, although you might get a “breakthrough” infection, you’re still very likely to be protected from severe disease or death. The important thing is to get fully vaccinated with 2 doses. It’s also important for everyone to get vaccinated, as the less effective the vaccine, the more we rely on one another to get vaccinated and protect each other.

Even with vaccines showing lower effectiveness against certain strains, the manufacturers are creating new versions of their vaccines to work better against these new variants, so that you can probably get booster doses in the future which will be effective in the months to come. One possibility is vaccines may be “mixed and matched”, so that people could have one jab that elicits a stronger cellular response and one that produces a higher antibody count.

For Pfizer-BioNTech, Moderna and AstraZeneca, two doses are needed because the first dose “primes” your body’s immune response: your body learns to make antibodies to fight COVID-19. The second dose “boosts” it for a stronger and longer-lasting immunity. Both doses are needed to provide full immunity.

The Johnson & Johnson‘s vaccine was tested and shown to protect people and provide immunity with a single dose.

Pfizer-BioNTech and Moderna: mRNA vaccines.

A small piece of mRNA that makes the COVID-19 spike protein enters your cells and teaches your body to make antibodies against the COVID-19 virus. Then the mRNA is destroyed within hours, leaving instructions behind. 

Astra Zeneca and J&J: viral vector vaccines.

These vaccines use a harmless virus (like the common cold virus) that has been weakened and then modified by adding a piece of the COVID-19 virus’s spike protein. The same process takes place as with mRNA vaccines above, triggering our body to make antibodies and to activate other immune cells.

None of them interact with or alter your own DNA!

None contain live COVID-19 virus.

All have similar side effects: pain at the injection site, tiredness, fever or flu like symptoms, headache, mild muscle/joint aches.

Health Canada has approved the Pfizer-BioNTech, Moderna, AstraZeneca and Janssen (Johnson & Johnson) COVID-19 vaccines for use in Canada.

No. Getting any vaccine, including the COVID-19 vaccine, will not affect the results of a COVID-19 test as it is not a live vaccine.

Most people who have COVID-19 recover completely within a few weeks. But some people — even those who had mild versions of the disease — still experience symptoms after their initial recovery. These people are known as COVID-19 “long haulers”.

Older people and people with many serious medical conditions are the most likely to experience lingering symptoms, but even young, otherwise healthy people can feel unwell for weeks to months after infection.

Common symptoms include fatigue, shortness of breath, cough, joint pain, chest pain, muscle pain or headache, fast or pounding heartbeat, loss of smell or taste, problems with memory/ concentration/ sleep, rash or hair loss.

COVID-19 can also cause organ damage to the heart, lungs, brain, including in younger people, and can weaken blood vessels and cause long-lasting liver and kidney problems.

In addition, it can cause long-term problems with mood and fatigue. Many long-term COVID-19 effects still unknown. This is why it’s important to continue to try to prevent spread of COVID by getting vaccinated, wearing masks and distancing when indoors in crowds.

While most children who contract COVID-19 are asymptomatic or have mild symptoms, those with a multi-system inflammatory response may have more severe reactions to the virus. Multi-system inflammatory response (MIS-C) is a rare condition that occurs when different parts of the body – including but not limited to the heart, lungs, and skin – become inflamed. Symptoms of the condition can include fevers, abdominal pain, cardiovascular problems, and neurological problems. MIS-C can develop and show a response 4-6 weeks post COVID-19 infection. Children with MIS-C have immune responses that react more aggressively to the virus, and rather than creating protection, the virus causes the immune system to attack tissues in the body. 60% of children with MIS-C are male, and the average age is 9. If MIS-C is identified in the early stages it can be treated, however if left untreated, it could be fatal.

Risk of MIS-C can be reduced by getting children vaccinated with the COVID-19 vaccines when they are eligible.