Measles is a respiratory disease caused by a highly contagious virus. It is a virus that is easily spread through the air, from person to person, through breathing, coughing or sneezing. Measles is the leading cause of vaccine-preventable deaths in children worldwide.

How measles spreads

  • If you come in contact with someone who has measles, you could develop symptoms about 7 to 21 days later.
  • Measles can spread if you have shared the same room or airspace with a person who has measles.
  • A person is contagious from four days before the rash begins until four days after the rash has appeared.
  • Measles can remain in the environment for up to two hours after an infected person has left the area.
  • If you have been exposed, you are at risk of developing the disease. Full vaccination reduces your chance of illness if you are exposed. You should contact your health care provider or public health unit if you have been exposed.

Symptoms of measles

  • Measles begins with cold-like symptoms such as a runny nose, cough, sore throat, fever, and red, watery eyes that are sensitive to light.
  • Small white spots sometimes appear in the mouth and back of the throat.
  • 3 to 7 days later, a red blotchy rash appears on the face and spreads to the rest of the body.
  • The rash lasts 4 to 7 days.
  • Serious complications can occur such as:
    • One in ten children will develop an ear infection or bronchopneumonia.
    • One in one thousand children will develop an infection of the brain (encephalitis).
    • One or two out of a thousand children will die as a result of measles.

Preventing measles with vaccination 

Vaccination against measles is almost 100% effective in preventing the illness for those who are fully vaccinated. 

Recommendations for children

  • Current Ontario recommendations are that children receive two doses of the measles-mumps-rubella (MMR) vaccine:
    • First dose on/after their first birthday
    • Second dose at 4 to 6 years old
    • For some infants 6 to 12 months of age, one dose of the measles-mumps-rubella (MMR) vaccine can provide protection if there is a risk of exposure.
  • The measles vaccine is required in Ontario for school-aged children. View your child's vaccine records online.

Recommendations for adults 

  • Health care workers or military personnel:
    • Two doses of the measles vaccine are recommended regardless of year of birth.
  • Born in 1970 or later:
    • Should have at least one dose of the measles vaccine.
    • A second dose is recommended for international travellers and post-secondary students.
  • Born before 1970:
    • Adults born before 1970 are considered to be immune to measles based on probable exposure earlier in life.
    • One dose of the measles vaccine is recommended for international travellers and post-secondary students.

Where to get vaccinated

Measles exposure 

If you think you have been exposed to measles:

  • Stay home if you are ill to avoid passing germs to others.
  • Seek medical attention when exposure is suspected and before any symptoms appear.
  • Those who notice possible symptoms are asked to stay home and call ahead before visiting a clinic.

Additional resources 

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