Measles

View all recent known measles exposures and timelines below, as well as a risk assessment tool to help you determine what actions to take if you were exposed. Always call ahead before seeking a medical assessment by a healthcare provider if your measles symptoms cannot be managed at home.

What is measles?

Measles is a highly contagious virus. It spreads easily through the air when someone with measles breathes, coughs, or sneezes.

Measles is a reportable disease of public health significance that can result in complications such as diarrhea, ear infections, and pneumonia. Rarely, measles can cause brain infections and death. 

Check or update your immunization record to make sure you and your family are up-to-date with vaccinations.

How many measles cases are there?

The epidemiology team at Southwestern Public Health publishes a weekly Measles Outbreak Report to provide an overview of the current measles situation in the region. It is published on Thursdays until further notice. This report is not intended to serve as a personal risk assessment tool for measles. You can view the report on our Surveillance and Dashboards page.

Measles exposure risk assessment

Click the red button to begin the assessment

Exposure Risk Assessment

Measles exposures

If you were present at the below locations during the timelines shown, you may have been exposed to measles. 

Woodstock Hospital - Emergency Department

310 Juliana Drive, Woodstock

  • May 9, 2025 - 4:21 PM to 6:36 PM
  • May 10, 2025 - 1:30 PM to 5:09 PM
  • May 10 2025 - 1:15 PM to 3:36 PM
  • May 11, 2025 - 12:07 PM to 2:22 PM
  • May 12, 2025 – 8:30 PM to 11:12 PM
  • May 13, 2025 – 9:03 AM to 5:23 PM

Woodstock Hospital - Diagnostic Imaging

310 Juliana Drive, Woodstock

  • April 26, 2025 - 12:30 PM to 2:30 PM

Alexandra Hospital, Ingersoll

29 Noxon St., Ingersoll, ON, N5C 1B8

  • May 8, 2025 - 3:25 PM to 6:15 PM 

Tillsonburg District Memorial Hospital - Emergency Department

167 Rolph Street, Tillsonburg

  • June 22, 2025 - 4:16 PM - 7:05 PM
  • June 24, 2025 - 10:01 AM - 12:30 PM

St. Thomas-Elgin General Hospital - Emergency Department

189 Elm Street, St. Thomas

  • May 3, 2025: 6:31 PM to 8:41 PM
  • May 4, 2025 - 12:00 PM to 2:20 PM (waiting room)

Aylmer Medical Clinic

424 Talbot St W. Aylmer, ON

  • May 15, 2025 - 10:30 AM to 1:00 PM

If you were born in 1970 or later, and are not up-to-date with your vaccinations, please call public health at 1-800-922-0096 ext. 1232. This includes those who were only there briefly on the dates and times shown.

A public exposure notice is issued when we are not confident that we can reach everyone who may have been exposed to measles in each situation. Public exposure notices are not required in situations when we are confident we have informed everyone who may have been exposed to measles. Read our news updates for more information.

What should you do if you were exposed to measles? 

Check immunization records

Make sure you and your family are up to date with measles vaccines (MMR or MMRV).

  • Most people need two doses if born in 1970 or later
  • People born before 1970 are usually considered protected
  • Check your immunization records or ask your health care provider to confirm

Watch for symptoms

Measles symptoms can appear up to 21 days after exposure. Even if you are vaccinated, stay alert for:

  • Fever
  • Cough, runny nose, red eyes
  • Rash that starts on the face and spreads

If you are not vaccinated, avoid contact with:

  • Pregnant individuals
  • Young children
  • People with weakened immune systems

Call before visiting a health care setting

If you think you have measles, were exposed, or are a close contact, call before visiting a doctor, hospital, clinic or any other health care setting. This helps protect others and allows health care providers to prepare for your visit.

Vaccination

The best way to protect against measles is vaccination. Two doses of measles-containing vaccine (MMR and/or MMRV) is 99 per cent effective in preventing a measles infection. 

The measles vaccine is a publicly funded, routine childhood vaccine in Ontario. Check your immunization records or ask your healthcare provider to confirm your vaccinations.

Eligibility for measles vaccination

Due to ongoing measles activity in the Southwestern Public Health region and in consultation with the Ministry of Health, measles vaccine eligibility has been expanded to include anyone who lives, works, attends school, travels to, or participates in activities (such as sports or worship) within the region.

Infants aged 6 months to 11 months are eligible to receive a dose of measles-containing vaccine for earlier protection against measles.

Because the infant immune system is less mature, these infants will still require two doses of measles-containing vaccine after one year of age. Typically, in Ontario, children receive their first dose of measles vaccine (MMR) at one year of age.

A second dose of measles-containing vaccine for children can be given before the age of four in consultation with your healthcare provider.

Typically, in Ontario, children receive a measles booster dose between the ages of four and six, preferably before starting school.

It is strongly recommended for under-immunized children who are in school or childcare to receive measles vaccine.

Adults born before 1970 are generally considered protected against measles. Adults born before 1970 who work in healthcare may be recommended to receive measles vaccine. Consult with your healthcare provider.

Adults born in 1970 or after are advised to have two doses of measles-containing vaccine. Many people would have received these as childhood immunizations. 

People who are pregnant or immunocompromised (have a weakened immune system) are generally not recommended to receive a measles-containing vaccine.

Consult a healthcare provider if you're not previously vaccinated and are at risk of exposure to measles.

Book a vaccine appointment

Frequently asked questions

Measles symptoms start 7 to 14 days after you are exposed to the virus. The main signs include:

  • High fever

  • Cough

  • Runny nose

  • Red, watery eyes

  • Red rash that starts on the face and spreads to the body

Complications can include:

  • Diarrhea

  • Ear infections

  • Pneumonia (lung infection)

Rare but serious complications:

  • Brain infection (encephalitis)

  • Death

Measles spreads when:

  • You breathe air where an infected person has coughed or sneezed

  • You touch a surface with the virus on it and then touch your eyes, nose, or mouth

  • The virus can live in the air or on surfaces for up to two hours

  • You can spread measles to others four days before the rash starts and until four days after the rash starts

  1. Get vaccinated: The best way to protect yourself is to get two doses of the measles vaccine (MMR or MMRV)

  2. Wash your hands often with soap and water

  3. Stay home if you feel sick

  4. Avoid crowds during a measles outbreak

If you think you have measles:

  1. Stay home and avoid contact with others. Learn more about isolation guidelines.

  2. Call ahead before you visit a doctor, clinic, or hospital so they can prepare for your arrival and prevent virus spread.

  3. Wear a mask if you need to go out for medical care. Check that you are wearing a high quality mask.

There are two vaccines:

  1. MMR – Protects against measles, mumps, and rubella

  2. MMRV – Protects against measles, mumps, rubella, and chickenpox

The first dose (MMR) is given soon after the first birthday, and the second dose (MMRV) is given at 4 to 6 years of age.

Outbreak note: Infants ages 6-11 months of age who live, play, travel to, worship in, or otherwise in the Southwestern Public Health or the Grand Erie Public Health region may be given an early dose of MMR vaccine. Two additional doses of measles-containing vaccine will still be required after the age of one year of age.

Measles is diagnosed through laboratory tests. These tests may include:

  • A swab of your nose or throat (nasopharyngeal or throat swab)

  • A urine sample

  • A blood test

There is no specific medicine to treat measles. Most people get better at home with rest and fluids.

Some people may need to go to the hospital if they get very sick.

 Measles vaccination is the best protection to prevent an infection.

You are at risk if:

  • You have not had two doses of the measles vaccine

  • You have never had measles before

The high-risk groups are:

  • Babies under 12 months old

  • Pregnant people

  • People with weak immune systems

If you’re not sure about your vaccine history, check your immunization record or talk to your health care provider.

Vaccination isn’t an option for some high-risk groups, such as infants under 6 months and pregnant individuals.

Because measles is currently circulating in the Southwestern Public Health region and neighbouring regions, people at higher risk may want to take extra precautions:

  • Make sure all household members are up to date with their measles vaccinations

  • Choose outdoor gatherings whenever possible, as they are safer than crowded indoor events

  • Attend or host events with clear expectations that anyone with measles symptoms or recent exposure should stay home

Measles is a reportable disease in Ontario, which means healthcare providers and hospitals must report suspected or confirmed cases to the local public health unit, like Southwestern Public Health.

Once a report is received, public health begins an investigation that includes risk assessment and contact tracing. If we cannot reach everyone who may have been exposed directly, we issue a public notice of a community exposure.

Anyone born in or after 1970 who has only had one dose of the measles vaccine is considered at risk. This includes children between 12 months and 4 years old who haven’t yet received their second dose. People with only one dose, including children, will be excluded from school or child care until they get their second dose. Once children get their second dose, they can return to school or child care.

Measles is currently circulating in under-vaccinated populations in the Southwestern Public Health region (St. Thomas, Oxford County and Elgin County). 

The best protection is vaccination. Two doses of MMR/MMRV vaccine provide up to 99 per cent lifelong protection.

If they have not had two doses of measles-containing vaccine, yes.

The Infectious Disease Protocol for Measles requires children who have only had one dose of the measles vaccine be kept out of high-risk places like school and child care. This means if your child has had just one dose, they will need to stay home from child care until they get the second dose. 

The typical immunization schedule in Ontario includes one dose of a measles-containing vaccine at 12 months of age, followed by a second dose at 4 to 6 years old. However, both the Canadian Immunization Guide and the Ontario Immunization Schedule (page 11) state that the minimum time between the two doses of the measles-containing vaccine can be as short as 4 weeks. Due to the unprecedented measles outbreak in our region, in consultation with the Ministry of Health and Public Health Ontario, earlier second doses are now recommended in keeping with these references. 

For more details, you can refer to the Ontario Immunization Schedule and the Canadian Immunization Guide. 

The Canadian Immunization Guide says that side effects from the MMR vaccine happen less often and are usually less serious than those caused by the actual diseases. Side effects are less common after the second dose and usually only happen in people who weren’t fully protected by the first dose. About 5% of children who get the MMR vaccine may have mild symptoms like feeling tired or having a fever (sometimes with a rash) 6 to 23 days after getting the vaccine, and these symptoms usually last up to 3 days. Sometimes, kids may also experience swelling of the glands, a rash, swollen lymph nodes, or joint pain after the vaccine. 

Additionally, Public health units have a strong system in place to track and follow up on any reactions after vaccinations, ensuring the safety of vaccines. The Public Health Agency of Canada also has a program to support and review vaccine safety: Vaccine Injury Support Program. 

If your child has had measles, they are usually only immune to measles. To protect against mumps and rubella (the other antigens in the MMR vaccine), it's recommended that they get two doses of the MMR vaccine. 

A doctor can check if your child is immune to measles after they’ve had it. However, getting two doses of the MMR vaccine is the best way to make sure your child is fully protected against all three diseases, rather than relying on natural immunity from measles alone. 

Please, do not risk your health or your child’s health through a measles infection. The safest way to become immune to measles is through vaccination.

A measles infection can have long term health concerns after the infection has passed. This can include seizures, hearing loss, intellectual disability, or other lasting neurological problems. Measles-related pneumonia can cause long-term respiratory issues or scarring in some children. And while rare, measles can result in a fatal brain disorder called Subacute Sclerosing Panencephalitis that can develop years after a child has measles. It causes progressive damage to the brain and is not curable.

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Southwestern Public Health (8:30 a.m. - 4:30 p.m., Monday - Friday)

St. Thomas Site
(Administrative office)
1230 Talbot Street
St. Thomas, ON N5P 1G9

Woodstock Site
410 Buller Street
Woodstock, ON N4S 4N2

Call us toll free: 1-800-922-0096
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