Vaccine safety

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Vaccine safety

Highlights
  • Vaccines are very safe. There are rarely reasons not to get vaccinated.
  • A number of studies have shown that giving combinations of vaccines is both safe and effective.
  • There is no evidence that side effects from vaccination are more common in younger infants.

Immunization is one of the most important ways to keep your child or teen healthy. Before vaccines were available, children often got very sick or even died from diseases that can now be prevented.

Vaccines are very safe. There are rarely reasons not to get vaccinated.

Who ensures that vaccines are safe?

Like all medicines, vaccines must go through a series of steps to be approved for use in Canada. Vaccines must be shown to be safe and effective in preventing the diseases they target. This review process is done by Health Canada.

Once a vaccine is approved, health authorities continue to make sure it is safe. One way is through a program called IMPACT (Immunization Monitoring Program, ACTive). Nurses at 12 children’s hospitals across Canada review hospital admissions for certain serious illnesses and use this information to find out if the illness could possibly be from vaccination.

Canadian doctors and nurses can also send a report to Health Canada if they see a patient with a serious health problem that happened after a vaccine.

Are there side effects to vaccines?

After getting a vaccine, some children will have a mild fever or feel pain or have redness where the needle went into the arm or leg. If necessary, acetaminophen (such as Tylenol, Tempra, Panadol and others) will help ease the pain.

Other side effects are very rare. The chance of getting sick from a vaccine-preventable disease is far greater than the very small risk of having a serious side effect from the vaccine itself.

How can I decrease pain my infant or child might feel with the vaccination injection?

HELPinKids offers tips on how to make vaccination as easy and pain-free as possible for infants and children – and even adults. Read A Guide for Parents or watch this video for tips.

Is it better to give vaccines one at a time or combined with others?

Many vaccines protect your child from multiple illnesses. For example, the 5-in-1 vaccine protects against diphtheria, polio, tetanus, pertussis and Haemophilus influenzae type B (Hib) disease. The MMR vaccine protects against measles, mumps and rubella. 

Several studies have shown that combination vaccines are both safe and effective. They also save time because your child receives several vaccinations during one visit. Fewer shots may also be less upsetting for your child.

A child’s immune system has no trouble handling many vaccines given together.

Is it safer to wait until my baby is older to start vaccination?

A baby’s vaccination schedule starts at 2 months of age to provide protection as early in life as possible. Many of the most serious diseases that we immunize against (such as meningitis) are most common in babies less than 6 months of age.

Can measles or MMR vaccine cause autism or other developmental disorders? 

No. There is NO scientific evidence to support this claim. 

Can mercury (thimerosal) in vaccines cause brain damage, retardation, autism, attention-deficit disorder, learning disorders? 

As of March 2001, all routine vaccines for children in Canada are produced without thimerosal.

Thimerosal (ethyl mercury) is a preservative used to produce vaccines stored in vials (containers) that have more than one dose, such as the some influenza vaccines. There is no evidence that thimerosal in vaccines causes any side effects or diseases in children.

Methyl mercury is a very different compound from ethyl mercury (thimerosal). Methyl mercury can cause serious disorders in children BUT no vaccines contain methyl mercury.

Large studies where some children received vaccines with thimerosal and others received thimerosal-free vaccines showed no difference in the number of children who developed autism. Thimerosal-containing vaccines are safe.

In Canada, the only vaccine with thimerosal is influenza vaccine in multidose vials. Some children may be given this influenza vaccine if single dose vials are not available.

Can immunization cause SIDS (sudden infant death syndrome)? 

Several large studies have found no link between vaccination and SIDS. In fact, all of these studies found that babies who died of SIDS were less likely to have been recently vaccinated than babies in the control group (babies chosen to match those who died of SIDS based on factors such as age, sex and weight to make comparisons). 

Can vaccines cause asthma and other kinds of allergic disease? 

Studies show that immunization does not increase the number of cases asthma and other allergic diseases in children. 

What are the risks of not vaccinating or not vaccinating on time?

The diseases prevented by infant and childhood vaccines are serious and even deadly. Measles can spread to the brain, cause brain damage and kill. Mumps can cause permanent deafness. Polio can cause paralysis. Sadly, these diseases have not disappeared. There is no treatment and no cure for diseases like measles, polio and tetanus. The only way to protect your child is through vaccination.   



Reviewed by the following CPS committees:
Infectious Diseases and Immunization Committee

Last updated: November 2013