Vaccines Work

Vaccines are a proven way to prevent serious infections. As a baby, child, youth, and adult, your family can be protected with vaccines. In this section you will learn more about the importance of vaccines, vaccine safety, and potential side effects. You will also get answers to some common myths and facts about vaccines.

Vaccine awareness is an important-focus for Ottawa Public Health. We are here to provide trustworthy, science-based information to help you better understand why they are such an important part of you and your family’s overall health.

What is the difference between vaccines, vaccinations, and immunizations?
You may see the words vaccine, vaccination and immunization across our website. A vaccine is the actual product being given to a person to protect them from a disease. Most vaccines are given by injection (with a needle) but some can be given orally (by mouth) or nasally (sprayed in the nose). Vaccination is the process of introducing a product (vaccine) to get protection from a particular disease and immunization is the process of being protected from a disease. All of these are to make sure you get immunity. Immunity means to have protection from a disease so that you can be exposed to a disease without becoming sick.
Why are vaccines important?
  • Vaccines protect people against very harmful and serious diseases like measles, polio, meningococcal, tetanus, diphtheria, and more. Vaccines are given to prevent you from getting a disease, before it has a chance to make you sick. This is different from most medicines that you take after you become sick.
  • Vaccines save lives: Vaccines have saved more lives in Canada than any other medical intervention in the past 50 years. The World Health Organization estimates that vaccines save 2-3 million lives worldwide every year. They also protect against diseases that may not be deadly but can cause pain and permanent disability.
  • These diseases do still exist:  Diseases like tetanus, whooping cough and the flu are continually present in Canada. Other diseases are common in parts of the world with different immunization programs from Canada. Due to international travel these diseases can come to Canada. It is important for us to maintain high rates of immunization to keep them from infecting others and spreading. 
If other people are immunized why do I need to be?
“Herd immunity” is when enough people are protected from a disease by vaccination that the disease cannot spread. Ideally, herd immunity is achieved when 95 % of the population has immunity against the disease. Diseases have the potential to spread if herd immunity is not reached. This can happen when vaccination rates decrease. Some people are not able to receive vaccines because they are too young, like babies or due to a medical reason, such as an allergy. These people rely on herd immunity to keep them safe.
How do I know that vaccines are safe?

Vaccines undergo a comprehensive review of their safety, quality and efficacy (how well they work) before they are approved and can be used in Canada. After approval, vaccines are continually monitored through a “vaccine safety surveillance” to ensure their safety.

Ottawa Public Health is involved in this surveillance process by investigating all reports of an Adverse Event Following Immunization (AEFI) and reporting them to Public Health Ontario.

An AEFI is a serious or unexpected reaction that happens after someone receives a vaccine, which may or may not be caused by the vaccine. In Ontario, health professionals like nurses and doctors are required to report AEFIs to their local public health unit like Ottawa Public Health. For more information on this process you can visit Public Health Ontario’s website.


What are the side effects of vaccines
Just like any medicine, vaccines can cause side effects.  Most of these side effects are minor and last only a day or two.

After your child receives a vaccine, you may notice that they:

  • are fussy
  • feel more sleepy than normal
  • have a low fever
  • have a sore, swollen, or red spot where the needle went in

These reactions are normal. You can give your child medicine to help with the pain or lower the fever. Ask your healthcare provider what medicine is best.

Serious reactions to vaccines are very rare. These may include:

  • a fever above 40°C (104°F)
  • crying or fussing for more than 24 hours
  • worsening swelling where the needle went in and/or
  • unusual sleepiness
  • hives
  • swelling of the mouth or throat
  • difficulty breathing, hoarseness or wheezing
  • fast heartbeat, dizziness

For any of these serious reactions, seek medical attention immediately.

You know your child best. If you notice anything that is not normal after a vaccination, check with your healthcare provider.

Myths and facts about vaccines
The Canadian Paediatric Society answers some of the common myths about vaccines that you may have heard about. For clarification regarding these myths, please visit the Canadian Paediatric Society’s website
There is so much information about vaccines. How do I know what is true?
With so much information at your fingertips, it can be challenging to know what to believe. Be it online or in print, make sure the information you are reading is up-to-date, and from a credible source. Talk about the information you have read with a trusted health care provider, like your family doctor or an Ottawa Public Health nurse.
The Canadian Paediatric Society provides some helpful tips to help you evaluate your immunization information.

Flu vaccine

If you have received a flu vaccine, it will not protect you from becoming infected with COVID-19, but will help prevent the flu (influenza). Getting the flu can make you very sick and could make you more vulnerable to other infections. Getting the flu vaccine is also an important way to prevent cases of the flu and help protect our health system this upcoming fall and winter.

Getting the flu vaccine will not increase your risk of illness from coronavirus, as demonstrated in this recently published Canadian research study.






Do you have more questions about parenting?

  • Connect with a registered nurse from Health811 for free, secure, and confidential health advice. Service is available 24/7 in English and French, with translation support also offered in other languages. Call 8-1-1 or visit
  • Connect with a Community Navigator from 2-1-1 for information about community programs and resources across Eastern Ontario. Helpline service is available 24/7 and in many different languages. Call 2-1-1 or visit
  • Connect with other parents on the Parenting in Ottawa Facebook page.
  • There are a variety of services to make it easier for your child to grow up healthy in Ottawa.
  • You can update your child's immunization record using either the CANImmunize App or the Immunization Connect Ontario (ICON) Tool
  • If you have received a message from Ottawa Public Health such as a letter or a call regarding immunization, an infectious disease, or infection control lapse, please call 613-580-6744 and listen to the menu options carefully.






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