Measles 

Measles is a highly contagious viral infection that spreads through the air when an infected person breathes, coughs or sneezes. It can result in complications such as pneumonia, ear infections, brain infections, other infections and infrequently, death can occur.

Table of Contents

• Possible Measles Exposures in the Middlesex-London Region
• What is measles?
• How is it spread?
• What do you do if you are exposed to measles?
• Signs and Symptoms
• What to do if you develop symptoms
• How is measles treated?
• How can measles be prevented?
• Vaccine information
• Day Campers and Day Camp Operators
• Travel Health Advice
• Healthcare Providers

How is it spread?

Measles is a virus that spreads easily through the air. It is transmitted in tiny droplets when an infected person coughs, sneezes or breathes. It can survive in the air for up to two hours. Measles can be spread from four days before the rash appears until four days after the onset of the rash.

What do you do if you are exposed to measles?

If you are born before 1970, have had measles in the past, or have received two doses of measles-containing vaccine you are considered protected against measles infection.

If you have been exposed and are not protected, a vaccine can prevent measles from developing if given within 72 hours (3 days) of exposure. These individuals should contact their health care provider, or the Middlesex-London Health Unit, at the phone number listed below as soon as possible. 

Pregnant women who are not protected, individuals who have problems with their immune system and are not protected, and infants under six (6) months of age can be treated with another medication up to six (6) days after exposure. These individuals should contact their health care provider, and the Middlesex-London Health Unit, at the phone number listed below as soon as possible. 

Signs and Symptoms:

• Fever, cough and runny nose
• Red, irritated eyes and light sensitivity
• Small white, grey or blue spots in the mouth
• Red, blotchy rash, which is the last symptom to appear. The rash appears on the face and then spreads down over the body, and will begin to fade after about a week.

Symptoms can start anywhere from 7 to 21 days after a person has been exposed to the virus. Symptoms usually develop around 10 days after exposure and the rash usually develops 14 days after exposure.

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What to do if you develop symptoms:

• Stay home and do not allow others to visit for at least four (4) days after the rash starts.
• Contact a healthcare provider as soon as possible and describe your symptoms over the phone. Because measles is so contagious, follow their instructions so that they can arrange to see you without exposing others to the virus.
• On arrival, immediately ask for a mask when you enter the office/clinic, and to be placed in a private room. If this is not possible, wait in your car until you are seen by the healthcare provider. 

How is measles treated?

There is no treatment for this viral illness. Supportive measures can be taken to relieve sore throat, cough and fever. Care should be taken not to expose others to infection by staying home and not allowing others to visit for at least four (4) days after the start of the rash. Immunization prior to exposure is the best defense against infection.

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How can measles be prevented?

Vaccines

Vaccines are a safe and very effective way to prevent measles. One dose of a measles-containing vaccine given after 12 months of age is up to 95% effective at preventing measles. Having two doses is about 99% effective.

On Tuesday, May 6, 2025, a memorandum was issued that provided guidance on the accelerated vaccine schedule for all public health unit regions in western Ontario due to increased transmission and community exposures. While the risk of measles to the general population remains low in Middlesex-London, the accelerated vaccine schedule is part of a coordinated response to the regional outbreak.

Measles outbreak accelerated vaccination recommendations:

Children

• Infants (six to 11 months) should receive one dose of the measles, mumps, rubella (MMR) vaccine.
• Note: Two additional doses are still required after the age of one year.
• Children (one to four years) who have received their first dose of MMR vaccine are encouraged to receive a second dose as soon as possible (at a minimum of four weeks from the first dose. This dose will count as the MMR component of the 4-6yr old booster dose, and will not need to be repeated after the age of 4yrs).

Adults

• Some adults may have received only one dose of the vaccine in the past. A second dose of MMR is recommended for anyone born in 1970 or later.
• Measles vaccine should not be given to pregnant people or individuals with immune system problems.

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Vaccine Details

The measles, mumps and rubella (MMR) vaccine is publicly funded and available at your healthcare provider's office.

The following schedule is recommended:

 Pregnancy and Breastfeeding

• Pregnant individuals who need the vaccine should wait until after giving birth to get vaccinated with MMR vaccine. People who are breastfeeding can be vaccinated with MMR vaccine.

Missing Vaccine Records

• If you are missing your vaccine records or unsure if you are immune, it is best to receive a dose of the MMR vaccine. It is safe to get extra doses of MMR vaccine, even if you are already immune.

Exposure to Individuals with Measles

• If you or a family member have been exposed to someone with measles, please check your immunization record, and follow instructions that will be posted by Public Health. You can also call your healthcare provider for more information.

Immunization Records

• If you're not sure about your vaccination status and whether you are up to date, please contact your healthcare provider. If you attended school in Ontario and are born after 1990, you may be able to access your records via Immunization Connect Ontario (ICON).

Day Campers and Day Camp Operators

Is your child attending a day camp this summer? While the overall risk of measles is low in the Middlesex-London region, it’s not gone. And measles spreads quickly among children in day camp settings if they are not fully vaccinated. How can you help?

• Make sure your children are up to date with their measles containing vaccines (MMR or MMRV) before camp starts.
• To be up to date, they will have had one vaccine at 12 months and a second vaccine between the ages of 4 and 6 (sometimes even earlier – speak to your health care provider).
• If your child is feeling unwell on a camp day, please keep them home until they are better.
• If your child is not yet fully vaccinated, please call your family health care provider or a walk-in clinic before camp starts.
• Make sure your child’s vaccination record is handy and up to date. You’ll need it if there is an exposure, case, or outbreak at your child’s camp.

Operating a day camp this summer? As you know, measles is spreading across Ontario this year and while the risk in Middlesex-London is relatively low, day camps must be prepared. How can you prepare?

• Communicate the importance of immunization to staff and parents and ask them to have vaccination records available in the event of an exposure, case, or outbreak.
• Learn the signs and symptoms of measles and how to report to public health.
• Ask parents to keep children at home if they feel sick – especially with respiratory symptoms (stuffy nose, cough, fever).
• Understand that both staff and campers who are not fully vaccinated may be excluded from camp if there is an exposure, case, or outbreak – limiting the availability of staff for up to 3 weeks.

Travel Health Advice 

Click here for information on travel health guidance.

Healthcare Providers

Access additional information intended for healthcare providers here.

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