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Facts About...


What is it?

  • The Measles, Mumps, and Rubella (MMR) vaccine, called M-M-R® II or Priorix® protects children against measles, mumps and rubella, all in one shot.
  • All three of these diseases are viruses that are spread easily from person to person.
  • For more information on these diseases, see Facts About... Measles, Facts About... Mumps and Facts About... Rubella.

How effective is the MMR vaccine?

  • The MMR vaccine protects against measles in close to 100% of those who receive two doses of vaccine.
  • It protects 76% to 95% of people against mumps and about 97% of people against rubella.
  • Someone who has had the vaccine may still get the diseases. However, the recovery is faster and the symptoms tend to be very mild.

Who should receive the vaccine?

The MMR vaccine is given in a series of two shots.

  • The first dose should be given on or after 12 months of age.
  • The second dose can be given at 18 months of age. However, it is recommended that the second dose be given as Measles, Mumps, Rubella, and Varicella (MMRV) at 4 to 6 years of age. See Facts About... Measles, Mumps, Rubella, Varicella Vaccine.

*In Ontario, two doses of MMR vaccination after the first birthday are required for school attendance under the Immunization of School Pupils Act.

NOTE: MMR and chickenpox vaccines MUST be given at the same visit or at least 28 days apart. If administered less than 28 days apart, the second of the two vaccines may not be effective.

  • This vaccine should also be given to adults who are not protected against measles, mumps or rubella. Talk to your health care provider to find out if you are fully protected.
  • Pregnant women are usually tested for rubella; if they are not protected against rubella, they should receive MMR vaccine when they are no longer pregnant. It is safe for breastfeeding mothers to receive MMR vaccine.
  • Infants aged 6-11 months can be vaccinated early if they are or may be exposed to one of the diseases (e.g., travel to a country where measles is common). They will still need to have two doses after their first birthday.

Are there side effects with the vaccine?

Most children have no side effects from the MMR vaccine. The most common side effects are:

  • redness, swelling, and tenderness at the site of the injection
  • fever
  • swelling of the glands
  • rash

Severe allergic reactions after vaccination are very rare and may not be related to the vaccine. However, if you think a serious reaction is developing, seek medical attention right away. Any unusual or significant changes in your health or your child’s health after receiving the vaccine should be reported to a health care provider and to the Health Department.

Who should NOT get the vaccine?

  • Infants less than 6 months of age (Note: Children at high risk of exposure who are vaccinated between 6-11 months of age will still require two additional doses after their first birthday).
  • Anyone who has a high fever or serious infection worse than a cold should defer the vaccine until they feel better.
  • Pregnant women or women considering pregnancy should avoid pregnancy for 4 weeks following vaccination.
  • Anyone who has had a serious allergic reaction (anaphylaxis) to a previous dose of MMR vaccine.
  • Any component in a vaccine may be a potential allergen. The most common for MMR are:

If you have any medical conditions, discuss the vaccine with a health care provider to determine if you should receive it.

Your record of protection

children in school or child care, please call the Health Department to update your child’s immunization records. Keep your records in a safe place!

*Parents must contact the Health Department if you object to immunization based on conscious or religious beliefs, or if your child cannot be immunized for medical reasons.


September 21, 2017

For more information call
905-668-7711 OR 1-800-841-2729