Vaccine safety

Vaccine Safety and the IMPACT Surveillance System

Did you know?

Vaccines are one of the most monitored and studied things in medicine because they are given to healthy children and adults.

Looking for more information about vaccine safety?

The Institute of Medicine is an expert group in the United States who have combed through scientific data from thousands of studies looking at adverse reactions after vaccines. Their full report, "Adverse Effects of Vaccines: Evidence and Causality" can be found here:

Vaccines are safe

Vaccines are safe, effective and necessary, with huge benefits — all through our lives. Vaccines are among the safest tools of modern medicine. The vast majority of side effects from vaccines are minor and temporary, such as a sore arm or mild fever. In Canada, serious side effects occur very rarely. For example, the risk of a severe allergic reaction is approximately one in a million doses of vaccine given. If this happens, it is most likely to occur within minutes after the vaccine is given. This is why you are asked to stay at the clinic or doctor’s office for 15 minutes afterwards. The nurse, doctor or pharmacist is prepared to treat this reaction.  

Vaccines are tested for many years 

Making a new vaccine that is effective and safe takes many years. Vaccines must pass several safety tests before they are ever given to people. On average, it takes about 10 years of research and development before a vaccine is considered for approval by Health Canada

Vaccine safety monitoring

After a vaccine has been approved for use and made available, its safety is continuously monitored. Every batch or ‘lot’ of vaccine is tested and approved by Health Canada before it is used. There are several systems in place in Canada and world-wide to monitor vaccine safety.

Health officials around the world take vaccine safety very seriously. That is why every parent is asked to call the public health nurse or family doctor to report any adverse events (unusual or unexpected side effects) following immunization. Adverse events following immunization are reported in each province and territory of Canada, as well as to the federal government and World Health Organization. Rates of these adverse events are analyzed and every serious event is reviewed in detail.

It’s safer to get the vaccine than to get the disease

Vaccines are safe — much safer than the diseases they prevent. As with any medical procedure, vaccines have some risks but these risks are very small. The risks from the diseases vaccines prevent are much greater. These diseases can cause pneumonia, deafness, brain damage, heart problems, blindness, paralysis and carry a risk of life-long disability or death. It’s much safer to get the vaccine than to get the disease. 

It’s just like…Worrying about the risks of the vaccine rather than the disease it prevents is a bit like being outside and constantly looking skyward because you are afraid you may get hit by an aircraft. As a result, you get hit by a car. Try not to focus on the wrong risk!

It is safe for your child to get more than one vaccine at a time

Even when your child gets several vaccines at the same time, most side effects will be mild and will last for only a day or two. Common side effects may include a low fever or soreness where the shot was given. Research shows that giving combinations of vaccines is both safe and effective and does not increase side effects. 

Vaccines do not cause illness or disease

Some people worry that vaccines can cause health problems, such as autism or sudden infant death syndrome (SIDS). Scientific evidence indicates that vaccines do not cause autism, multiple sclerosis, diabetes, sudden infant death syndrome (SIDS), or other illnesses. These studies are posted on the Institute of Medicine website at:

The ingredients in vaccines are safe

Some people are concerned about the safety of ingredients found in vaccines. However, people can be reassured that ingredients in vaccines are safe. Their use has not been linked to disease or illness.

Vaccines are made with ingredients that make them safe and effective.  Each vaccine contains a small amount of the disease germ (virus/bacteria) or parts of the germ. Examples are the measles virus, pertussis (whooping cough) bacteria, and tetanus toxoid. The germs are either dead or weakened, and the toxoids can not cause disease. Vaccines help your child's immune system build protection against disease. 

Other ingredients in vaccines help keep them stable and prevent contamination of multi-dose vials by bacteria and fungi. Some vaccines have ingredients to boost the immune response to the vaccine. Below are some of the ingredients in vaccines.

 Vaccine Safety Infographic

Antibiotics- Antibiotics are used in some vaccines to prevent bacterial contamination when the vaccine is being made.

Did you know?

Aluminum is present in breast milk and in infant formula in similar amounts as in vaccines. This amount is very small and extremely safe for infants.

Aluminum – Aluminum has been present in vaccines for over 70 years with no reported serious adverse reactions. Aluminum salts are added to vaccines to help them work faster, better and longer. Because we add aluminum to vaccines, significantly fewer antigens (pieces of the germ that the immune system recognizes) are needed to produce a good immune response. As a result, there are fewer side effects from the vaccine. We are constantly in contact with aluminum. It is the most abundant element in the earth's crust and is found in air, food and water. Aluminum is present in the infant's body from birth, and in breast milk and in infant formula. For example, in the first 6 months of life, infants are exposed to approximately 4mg of aluminum in vaccines. In this same time period, they are exposed to approximately 10mg of aluminum in breast milk, 40mg in infant formula, and 120mg in soy formula.

Although aluminum from food is absorbed into the blood much less easily than aluminum from vaccines, aluminum from any source is rapidly removed from the body. Aluminum is picked up in the blood and taken to the kidneys quickly - about half of aluminum in food or in vaccines is eliminated from the body by the kidneys in less than 24hrs, more than three-quarters is eliminated within two weeks and virtually all is eliminated within three years.

In order for aluminum to be harmful, three things have to happen. First, the kidneys must not be working well, or at all, and second, the amount of aluminum entering the body must be very large (hundreds or thousands of times larger than vaccines) and third, it must be constantly given over long periods of time (months or years) so that the body does not have a chance to clear it.

Did you know?

There is approximately ten times the amount of formaldehyde in a baby's body at any time than there is in a vaccine.

Formaldehyde – Formaldehyde is used to inactivate bacterial products or viruses used in some vaccines. Most formaldehyde is removed from the vaccine before it is packaged. Formaldehyde is naturally produced by the human body because it is required for the body to make DNA and proteins. Humans break down formaldehyde quickly, so it does not build up in the body.

Gelatin – Gelatin is contained in some vaccines to protect the vaccine from adverse conditions such as freeze-drying or heat. The gelatin in vaccines is prepared from cows and pigs.

Did you know?

Eating a can of white albacore tuna exposes you to two and a half times the amount of mercury in a flu shot, and the mercury found in vaccines is excreted from the body much faster.

Do vaccines contain thimerosal?

In B.C., thimerosal has not been used in any routine childhood vaccine since 2001, except for the flu vaccine. Thimerosal is a mercury-containing preservative present in small amounts in the flu vaccine to prevent bacterial and fungal growth. If a person received a vaccine contaminated with bacteria or fungi, he/she could get sick.

A large number of studies have shown no link between the use of vaccines containing thimerosal and harm to children. These studies are posted on the Institute of Medicine of the National Academies website at:{43C096A7-F094-43D0-985A-B6BF561A7C5D}.

Canada's Vaccine Safety Program 

Canada’s vaccine safety program is responsible for strictly regulating and monitoring all aspects of vaccine development and safety in Canada.  

Components of Canada’s vaccine safety program: 

  1. Pre-licensure review and approval: Data on the safety, stability and how well the vaccine works are thoroughly reviewed by the government regulatory body before a vaccine is approved.
  2. Current good manufacturing practices: Vaccine manufacturers must follow internationally-recognized manufacturing practices, and government inspectors may randomly inspect their facilities.
  3. Lot assessment before release: Every batch or ‘lot’ of vaccine must be tested for potency, safety and purity before release, including possible testing by government inspectors.
  4. Independent expert review of national vaccine recommendations: A group of independent experts review data related to vaccine safety and how well the vaccine works.  Recommendations resulting from this review are published.
  5. Post-marketing surveillance for adverse events: All healthcare providers and vaccine manufacturers must report adverse events, and the data is analyzed and published.
  6. Rapid Response to vaccine performance concerns: The use of a vaccine, or a particular lot of a vaccine, is stopped immediately if there are any concerns about its safety.
  7. Expert causality assessment of serious adverse events following immunization: Serious adverse events (e.g., deaths, hospitalizations) are carefully reviewed by a group of independent experts to determine the cause.
  8. International collaboration: Data on adverse events and other concerns are sent to the World Health Organization, and this information is shared with all countries.

For more information on the components of Canada's vaccine safety program, see the Canadian Paediatric Society Practice Point: Canada’s vaccine safety program.