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MMR vaccine: Myths and facts

Immunization is one of the most important ways to keep your child healthy. Vaccines are very safe. There are rarely reasons to not get vaccinated.

The MMR vaccine protects children against measles, mumps, and rubella. These are dangerous, even deadly diseases. Before the vaccine was approved in 1963, almost everyone got measles by the age of 18. In Canada, there were about 300,000 cases of measles every year. Since the vaccine, that number has fallen to less than 20 cases a year.

Children should get the MMR shot twice to have ongoing protection from infection. Provinces vary on the timing for the second shot.

  • The first shot is given at 12 months of age.
  • The second shot is given at 18 months OR between ages 4 to 6 years (before your child starts school).

MYTH: No one gets these diseases anymore. My child doesn’t need the vaccine.

FACT: When immunization rates drop, these diseases come back. Worldwide, measles kills 250,000 children every year. Outbreaks of measles, mumps and rubella still happen in Canada, especially in communities where many people are not vaccinated. Measles is also common in less developed parts of the world, including some of the Caribbean vacation islands.

MYTH: These diseases are not serious.

FACT: Before vaccines were available, *measles* killed several hundred Canadians each year. *Mumps* was the most common cause of meningitis, and often caused deafness.  If a woman is not protected and gets rubella in the early part of her pregnancy, her baby may be born with serious problems such as heart, eye and neurological (brain and spinal cord) problems. If a man is not protected and gets mumps as an adult, he can become sterile (not able to get a woman pregnant). The older a person is, the worse the risk of complications from these illnesses. That’s why it is so important to get the MMR vaccine at a young age.

MYTH: It’s better to get the vaccines one at a time.

FACT: Many childhood shots have several vaccines in them, including MMR. Studies show that combination vaccines are safe and effective. There is no reason for your child to get the vaccines one at a time. Getting the 3 vaccines at once also means your child is protected right away, has fewer medical visits, and has fewer needles (which can be less traumatic).

MYTH: The MMR vaccine causes autism.

FACT: The MMR vaccine does not cause autism. There is NO scientific evidence to support the theory of a link. Because signs of autism may appear around the same age that children receive the MMR vaccine, some parents believe the vaccine causes the condition. Much of the controversy over the MMR vaccine and autism came from a paper published in 1998 that suggested a link. But since then, 10 of the 13 authors of that paper have said they should not have come to this conclusion. Many large studies around the world have found no link between the MMR vaccine and autism.

The number of children with autism seems to have increased in recent years. But the increase happened long after children started to get the MMR vaccine. There are many theories as to why cases of autism seem to be on the rise. Some experts believe it’s because an autism diagnosis now includes children with milder symptoms. There is also greater public awareness of autism, and more parents are seeking help. Scientists also recently found a gene linked to autism.

MYTH: The thimerosal in vaccines causes autism and other disorders. 

FACT: There is no evidence that thimerosal (a mercury-based preservative) in vaccines causes these illnesses in children. As well, all routine childhood vaccines in Canada—including MMR—are made without thimerosal.

FACT: Vaccines are safe and effective.

Like all medicines, vaccines must go through many steps before Health Canada approves them for use. Vaccines must prove to be safe and effective at preventing the diseases they target. Once a vaccine is in use, Canadian health authorities continue to monitor for side effects.

Serious side effects to vaccines are very rare. Some children feel pain where the needle went in to the arm or leg and may develop a fever or rash several days after getting the vaccine. Taking acetaminophen before or after a vaccination can help.



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

Last Updated: December 2008

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