Vaccines for children: About vaccines

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Vaccination and the immune system

The immune system is a complex network of cells, tissues and organs that help prevent diseases and keep us healthy. Our immune system responds to bacteria and viruses that it considers unfamiliar or harmful that can make us sick.

Vaccines work with the body's natural defences to develop protection against diseases without the risks that come from getting the diseases themselves.

Our body produces antibodies and memory cells to fight infections and provide quicker protection against future infections. Antibodies are proteins that attach to harmful bacteria or viruses and help to remove them from the body. If we encounter that virus or bacteria again, memory cells quickly produce more antibodies to help remove it from our body faster.

Vaccination works by safely exposing our body to key parts of bacteria or viruses, called antigens. Antigens cause the immune system to react by creating antibodies and memory cells. Later, if we’re exposed to that same bacteria or virus, our immune system will be able to respond more quickly to:

How vaccines are given

Most vaccines are given with a needle into your child's upper arm or thigh. Some vaccines can be given by mouth, and there’s a flu vaccine that's sprayed into the nose.

Some vaccines protect against only one virus or bacteria, while combination vaccines protect against several at the same time. The immune system can respond to many antigens at once. Combination vaccines allow our bodies to build immunity to multiple vaccine-preventable diseases at once.

Children may need multiple doses of a vaccine to provide good protection. For example, DTaP-IPV-Hib is a combination vaccine which is generally given as 4 doses during the first 2 years of life. It protects against:

Some vaccines provide life-long protection, while others need booster doses to continue providing protection throughout your child’s life.

Development and approval of vaccines

For over 50 years, vaccines have:

Researchers all over the world continue to develop vaccines for diseases that harm the health of people and communities.

Once scientists develop a new vaccine, it goes through different tests to assess safety. These tests also determine how well the vaccine works to protect against disease. With all the available scientific information, the manufacturer then submits an application for the vaccine to be reviewed by Health Canada.

Health Canada carefully reviews all the available information. Only vaccines that meet the safety, effectiveness and quality criteria of Health Canada are approved for use.

Once a vaccine has been approved, Health Canada continues to monitor its safety and effectiveness based on information collected from:

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Vaccine effectiveness

Some vaccines work very well to prevent us from getting infected with a virus or bacteria, such as the measles or meningococcal vaccines. Other vaccines may decrease our chances of getting infected. However, if we do get infected, these vaccines help to prevent us from getting really sick, such as the flu and COVID-19 vaccines.

Vaccines that are part of routine childhood vaccination programs in Canada can protect your child againstserious diseases. It’s important for children to get all recommended vaccinations on time to get the best protection against these diseases.

Vaccines for children: Diseases that vaccination protects against

Community immunity and disease prevention

Some vaccines can help to create community immunity (also known as herd immunity). This means that the more people who have been vaccinated against a disease in a community, the less chance there is of the disease spreading in that community.

When you vaccinate your child, you help to protect them as well as those around them. Community immunity helps protect people:

Canada has set the goal that at least 95% of children in Canada receive all recommended childhood vaccines. Achieving this coverage level will help ensure that children are protected through routine vaccination and contribute to community immunity.

Vaccine side effects

Children may have mild side effects after vaccination because their bodies are working to develop an immune response.

In some cases, your child may:

This is normal. These mild reactions go away by themselves within hours to a few days.

You can give your child medication to help with the pain or to lower a fever if needed. Check with your child's health care provider if you need advice about which medication to use.

Serious allergic reactions to a vaccine are very rare. Signs may include:

If your child has symptoms that could be an allergic reaction, seek immediate medical attention.

Also contact your health care provider or seek medical attention if:

Tell your health care provider about any serious reactions your child has experienced before they receive future vaccinations. Your health care provider can then determine how best to manage future vaccinations that are needed.

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Vaccine safety monitoring

Canada has strong vaccine safety surveillance systems that work together to make sure vaccines are as safe as possible. The systems involve:

Health care providers report any unusual or serious events after vaccination to their local public health unit. After further investigation, this information is sent to provincial and territorial public health units, and then to the Public Health Agency of Canada. In collaboration with information with other countries and the manufacturer, these systems work to ensure the safety of vaccines given to children.

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Why vaccination is important

Keeping up to date on your child’s routine vaccinations will help to:

Science and history have shown that vaccination is one of the best tools to protect us from certain infectious diseases. Vaccines have successfully lowered the rates of disease in countries with strong vaccination programs. Some childhood diseases that were once common in Canada are now rare because of vaccines.

Vaccines can even completely stop an infectious disease from occurring anywhere in the world. Thanks to vaccination, there hasn't been a single case of naturally occurring smallpox in the entire world since 1977.

Compare number of cases for 6 vaccine-preventable diseases before and after vaccines were introduced in Canada

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