Vaccination for COVID-19 – Frequently asked questions

Person in white lab coat holding small vial

The Canadian Red Cross is encouraged by the continued administration of COVID-19 vaccines across the country and reminds people to continue to seek information from a trustworthy source, including the Public Health Agency of Canada and local and provincial health authorities.

As we move towards widespread, lasting control of COVID-19 through safe and effective vaccines, it’s essential for everyone in Canada to continue following public health recommendations to prevent further spread. It is more crucial than ever that people remain vigilant. We encourage everyone, including those who are vaccinated, to continue physical distancing, practice frequent hand hygiene, wear face masks, and follow any additional measures laid out by public health authorities across the country.

Is the vaccine considered to be effective and safe?

We understand there may be some misinformation circulating about the COVID-19 vaccine and its effects. It is essential for people to follow trusted sources for accurate and up-to-date information about vaccines, including the Public Health Agency of Canada and local and provincial health authorities.

The role of the Canadian Red Cross is to support vaccination efforts in coordination with local health authorities. The Red Cross does not replace Health Canada, which approves vaccines and determines risk and efficacy using evidence-based global standards.

Learn more about approved vaccines on Public Health Canada website

The COVID-19 vaccine was developed so quickly, how can it be trusted?

COVID-19 vaccines have been developed without compromising quality, safety, and effectiveness. It may appear they have been developed very quickly, but researchers around the world have been working hard to develop COVID-19 vaccines from the earliest stages of the pandemic. The vaccines for COVID-19 have been through the same amount of testing and safety processes as other vaccines.

Vaccines approved for use in Canada are reviewed through Health Canada’s independent drug authorization process, which is recognized around the world for its high standards and rigorous review.

Learn more about how vaccines are developed on this video from Public Health Canada

Can the vaccine give me COVID-19?

No. None of the COVID-19 vaccines approved in Canada use the live virus that causes COVID-19. It usually takes the body a few weeks to build immunity after receiving a vaccine. It is possible that someone could become infected with the COVID-19 virus before or just after getting the vaccine and get sick. This happens because the vaccine has not had enough time to provide protection in the body.

How do we know there won’t be long-term side effects?
Although it’s true there are still a lot of things we’re learning about the vaccines — like how effective they are against variants and how long their protection lasts — there are plenty of things we do know that give experts confidence in the long-term safety of the vaccines. For example, history tells us that severe side effects are extremely rare, and if they do occur, they usually happen within the first two months. Once a vaccine is approved, scientists and government agencies continue to monitor its safety to identify any rare side effects. These monitoring efforts also focus on particularly vulnerable people, including people with specific medical conditions, or pregnant women.

Can mRNA vaccines change my DNA?

No. mRNA is not able to alter or modify a person’s genetic makeup (DNA). The mRNA from a COVID-19 vaccine never enters the nucleus of the cell, which is where our DNA are kept. This means the mRNA does not affect or interact with our DNA in any way. Instead, COVID-19 vaccines that use mRNA work with the body’s natural defenses to safely develop protection (immunity) to disease.

Can people who have already tested positive for COVID-19 get the vaccine?

Yes. Due to the severe health risks associated with COVID-19 and the fact that re-infection with COVID-19 is possible, people should still get vaccinated even if they have been sick with COVID-19 before. While infection alone provides some protection, vaccination after infection helps improve the immune response and may provide better and longer-lasting protection.

Are the vaccines safe for people who are immunosuppressed due to disease or treatment?

For those who are moderately to severely immunocompromised in the authorized age group who have not yet been immunized, NACI recommends that a primary series of three doses of an authorized mRNA vaccine should be offered. For those who are moderately to severely immunocompromised in the authorized age group who have previously received a 1- or 2-dose COVID-19 vaccine, NACI recommends that an additional dose of an authorized mRNA COVID-19 vaccine should be offered.

How quickly does the vaccine work? How long does it last?

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.

We don't yet know for sure how long protection will last. It is likely to be at least several months, but it may be that repeat vaccinations are needed. Researchers are studying this closely. The primary data shows that fully vaccinated individuals maintain a good level of protection up to 6 months from the date they received their last dose.

Learn more on Vaccine Efficacy Rates

If I get a COVID-19 vaccine, will I still need to take other precautions such as physical distancing and wearing masks?

Yes, you should continue following all public health guidelines in your area. Your vaccination status only changes your risk of getting COVID-19 and becoming sick. It doesn't change your risk of exposure to the virus out in the community. It is important that you continue to follow all public health guidelines to protect yourself, your loved ones and your community.

Will COVID-19 vaccines provide long-term protection?

Ongoing research is needed to show if COVID-19 vaccines provide long-term protection. Additional doses of the vaccine may be needed to provide continued protection. It will take ongoing evaluation over several years to understand how our immune systems respond to this virus and how vaccines assist in that response.

The National Advisory Committee on Immunization (NACI) has reviewed the latest data that suggest protection against infection decreases over time since completion of a primary COVID-19 vaccine series. Protection against severe illness remains generally high, but may decrease over time for some people, such as older adults.

NACI recommends that a booster dose of an authorized mRNA COVID-19 vaccine may be offered 6 months after completion of a primary COVID-19 vaccine series to eligible population groups with consideration of jurisdictional and individual risks.

Should children be vaccinated?

As of November 19, 2021 NACI recommends a complete series of the Pfizer-BioNTech COVID-19 vaccine (10 mcg) may be offered to children 5 to 11 years of age who do not have contraindications to the vaccine, with a dosing interval of at least 8 weeks between the first and second dose. All children and youth aged 6 months to 17 years can receive a COVID-19 vaccine. Only mRNA vaccines are approved for use in children and youth.

The Pfizer-BioNtech and Moderna vaccines are also approved by Health Canada for people 12 years of age or older. The National Advisory Committee on Immunization (NACI) recommends an interval of eight weeks between first and second dose to provide the strongest possible protection against COVID-19.

I think I have a low risk of contacting COVID-19, do I need to be vaccinated?

Anyone, at any age, can get sick with COVID-19 and become seriously ill or die and there’s no way to tell how it will affect you. Furthermore, asymptomatic people infected with the virus can be contagious and the virus can spread from them to other people especially youth who could serve as "super spreaders". For these reasons, it is important to consider that getting vaccinated may also protect people around you, particularly people at increased risk for severe illness from COVID-19. The currently authorized COVID-19 vaccines have been shown to be highly effective at preventing COVID-19 symptoms, and particularly severe illness or death.

Does the COVID-19 vaccine protect me from new strains of the virus?

According to National Advisory Committee on Immunization (NACI), while new evidence continues to emerge about the variants of concern, their transmissibility, virulence, and the effectiveness of COVID-19 vaccines against them, evidence has so far found that two doses of an mRNA vaccine is at least 88 per cent effective against the variants of concern. However, one dose of the vaccines has been found to be significantly less effective against the newer variants (as low as 33 per cent). This is why it is important to get vaccinated with the second dose as soon as it becomes available to you and to continue practicing other public health measures such as wearing masks and physical distancing.

The Omicron variant has been shown to be much more transmissible than the Delta variant and has some vaccine immune escape. It is unknown if the disease severity will be different than other circulating variants. The World Health Organization technical body said recently that current COVID-19 vaccines may need to be reworked to ensure they are effective against Omicron and future variants of the coronavirus. However Current figures suggest that vaccines offer 30 to 40 percent protection against infection and around 70 percent protection against hospitalization without boosters. Newer data is confirming that a third dose increases antibody production and boosts effectiveness against infection to around 75 percent, and 88 percent for severe disease.

Should I get my 4th dose now or wait for the Omicron-specific vaccines to be ready in the Fall?

COVID-19 vaccines remain our single most important tool to protect people against serious illness, hospitalization, and death. Given the recent increase in hospitalization seen in other countries associated with the B.A.5 variant, it is recommended to stay up to date with COVID-19 vaccinations, including additional booster doses. Those over 50 — or people with preexisting chronic or immunodeficiency conditions that place them at a higher risk for severe disease are highly recommended to get additional doses as soon as they become eligible as per the provincial criteria.

Getting vaccinated now will not prevent you from getting an authorized variant-specific vaccine in the fall or winter when they are recommended for you. From a population health perspective, the protection supplied by the second booster helps ensure that healthcare resources are capable of responding to the full spectrum of medical needs, reducing the chance of overwhelming health systems with COVID-19-related disease.

More information from official sources

Vaccines and treatments for COVID-19: Progress - Health Canada
Coronavirus disease (COVID-19): Vaccines - World Health Organization