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Immunization

Immunization benefits and safety

Learn about vaccine safety and how getting immunized protects you and your community.

Why immunization is important

When you get immunized (get a vaccine), it starts your body’s natural immune response to a disease. Your body begins to make antibodies that protect you against the disease before you have contact with it. This is the process of becoming immunized or building immunity.

Without a vaccine, your body likely does not have the antibodies to fight many of the diseases that vaccines can prevent. This means you and your family could get very sick.

Getting immunized lets you build immunity against disease, before being exposed to it. Immunization helps your body fight the disease faster and can prevent you from getting the disease. It also helps to prevent diseases from spreading to others.

Over the past 50 years, immunization has saved more lives in Canada than any other treatment, procedure, or policy against disease.

The impact of vaccines over the years.

Polio

Polio can lead to paralysis (not being able to move all or part of your body) and death. Before immunization, polio infected more than 5,000 Canadians every year. Thanks to the polio vaccine, between 2016 and 2020, there were 0 cases reported.

Diphtheria

In children under 5 years and adults older than 40 years, 2 to 4 out of 10 people who get diphtheria can die. Before immunization, diphtheria infected more than 9,000 Canadians every year. Thanks to the diphtheria vaccine, between 2016 and 2020, the highest number of cases reported in any year was 10.

Measles

1 in 1,000 people with measles will get encephalitis (swelling of the brain), which can lead to seizures, deafness, or brain damage. Before immunization, measles infected more than 60,000 Canadians every year. Thanks to the measles vaccine, between 2016 and 2020, the most cases reported in any year was about 100.

Rubella

If you get rubella while you're pregnant, it can cause loss of a baby during pregnancy or the baby may be born with disabilities. Before immunization, rubella infected more than 37,000 Canadians every year. Thanks to the rubella vaccine, between 2016 and 2020, the highest number of cases reported in any year was 1.

Invasive Hib

Hib can cause meningitis and lead to lifelong disabilities and death. Before immunization, invasive Hib infected more than 600 Canadians every year, and it was the most common cause of bacterial meningitis in children. Thanks to the Hib vaccine, between 2016 and 2020, the most cases of invasive Hib reported in a year was less than 20.

Pertussis (whooping cough)

In Canada 1 to 4 deaths are related to pertussis each year, most often in babies. Before immunization, pertussis infected almost 20,000 Canadians every year. Thanks to the pertussis vaccine, between 2016 and 2020, the most cases reported in any year was less than 4,000.

Healthy communities

When you and your family get immunized with a vaccine, you’re protecting yourselves and helping to build your community’s defence against diseases.

The more people in a community who are immunized, the less a disease can spread.

For immunization to protect your community from certain diseases, most people in your community need to be immunized. This is often called “herd immunity.”

Herd immunity is important to protect people who are at high risk of getting very sick—including young babies, older adults, people having cancer treatment or who have had an organ transplant—who cannot get a vaccine. They rely on those around them to get immunized to help protect them from disease.

By getting immunized, you’re helping to protect your vulnerable neighbours and your community.

Vaccine safety in Canada

Vaccine safety is a top priority. Canada uses extremely safe vaccines. Here is information about Canada’s vaccine safety system:

Testing for safety

All vaccines are tested fully before they are approved for use in Canada.
Vaccine manufacturers must prove to Health Canada that their vaccines are safe and protect against disease.
Every batch of vaccine that is made is tested. Health Canada reviews the test results to make sure every batch is safe and effective before it can be used.
The National Advisory Committee on Immunization reviews all safety information for approved vaccines and recommends how the vaccines will be used in Canada.

Monitoring for continued safety

Health Canada monitors all phases of vaccine production.
After vaccines are approved for use, they are continuously monitored to make sure they are safe and benefit Canadians.
The Canadian Adverse Events Following Immunization Surveillance System is always monitoring the safety of vaccines. They watch how often side effects happen and identify any new side effects.

Reporting and monitoring side effects

Vaccine manufacturers must give Health Canada information about any side effects reported during the clinical trials.
After a vaccine is approved for use in Canada, side effects are reported to the Canadian Adverse Events Following Immunization Surveillance System. If safety issues are identified, Health Canada investigates these issues to find out if the benefit of the vaccine continues to outweigh the risk. Vaccine information is updated with new information about precautions or side effects.

Immunization is very safe. It’s much safer to get the vaccine than to get the diseases that vaccines can prevent.

Ingredients

Vaccines contain ingredients to help prevent disease. They also contain small amounts of other ingredients to help keep vaccines safe and effective.

For a full list of vaccine ingredients go to Content of Immunizing Agents Authorized for Use in Canada. This is a list of ingredients for vaccines that are approved for use in Canada.

Vaccines may include

Aluminum salts

These may be added to a vaccine to help you have a stronger natural immune response to a vaccine. Aluminum is found in air, food, and water. The amount of aluminum in a vaccine is similar to the amount of aluminum in breastmilk and infant formula.

Formaldehyde

This is used in the manufacturing process of some vaccines to make viruses and toxins harmless. The formaldehyde is then removed, leaving only very small amounts that are safe.

Formaldehyde is produced naturally in the human body. A baby’s body naturally has about 10 times more formaldehyde than there is in 1 dose of a vaccine.

Thimerosal

Only some influenza (flu) vaccines contain thimerosal, a preservative used to stop any germs from making the vaccine unsafe. Routine childhood vaccines (in Canada) do not contain thimerosal. Learn more about thimerosal in vaccines.

Vaccines do not include

Mercury

Methylmercury is not in vaccines. Thimerosal contains a very small amount of a form of mercury, called ethylmercury. Ethylmercury leaves your body quickly through your stool (poop). It does not build up in your body like methylmercury.

Cells from aborted fetuses or other human cells

Human cell lines may be used in the early development of some vaccines, but all cells are removed during the purification of the vaccine. Similarly, human cell lines are used to test and develop many common medicines, including antacids and cold medicines.

Vaccines contain additional ingredients to help keep the vaccines safe and effective.

Side effects

The most common side effects after getting a vaccine are redness and swelling or pain in the area where you get the needle. These symptoms usually go away in 1 to 3 days.
It’s important to stay at the clinic for 15 minutes after getting your vaccine. Some people may have a rare but serious allergic reaction called anaphylaxis. If anaphylaxis happens, you will get medicine to treat the symptoms.
In Canada, severe allergic reactions to vaccines are very rare. For every 1 million doses of vaccines given, there is only about 1 severe reaction.
The vaccines that you and your family can get in Alberta are very safe. The diseases that vaccines protect you from can be dangerous.
These diseases put people at risk for serious health issues, such as hearing loss, paralysis, brain damage, and heart damage. The risk of these health issues is much higher than the risk of any side effects from a vaccine.

It is much safer to get a vaccine than to get the diseases that vaccines can prevent.

Allergies

Before getting a vaccine, always talk to your healthcare provider about any allergies you or your child may have. Your healthcare provider will recommend what is safe based on health history, including allergies.
If you are allergic to eggs, it’s safe to be immunized. MMR, MMR-Var, and influenza vaccines may contain tiny amounts of egg protein. Studies show that the amount of egg protein in these vaccines is too small to cause an allergic reaction in people who are allergic to eggs.
There is no evidence that vaccines cause allergies. Research about vaccines and allergies is still being done, but we do know that the benefits of vaccines are much greater than the risk of developing an allergy.

The benefits of vaccines are much greater than the risk of developing an allergy.

Related information

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Schedule an appointment for you or your child.

Current as of: October 26, 2023
Author: Provincial Immunization Program, Alberta Health Services

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Our work takes place on historical and contemporary Indigenous lands, including the territories of Treaty 6, Treaty 7 & Treaty 8 and the homeland of the Métis Nation of Alberta and 8 Métis Settlements. We also acknowledge the many Indigenous communities that have been forged in urban centres across Alberta.

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Content Editor

Immunization benefits and safety

Why immunization is important

The impact of vaccines over the years.

Polio

Diphtheria

Measles

Rubella

Invasive Hib

Pertussis (whooping cough)

Healthy communities

Vaccine safety in Canada

Testing for safety

Monitoring for continued safety

Reporting and monitoring side effects

Ingredients

Vaccines may include

Aluminum salts

Formaldehyde

Thimerosal

Vaccines do not include

Mercury

Cells from aborted fetuses or other human cells

Side effects

Allergies

Related information

Immunization benefits and safety