On March 14, 2025 the Chief Medical Officer of Health in Ontario released a statement that recommends all Ontarians should ensure themselves, and their children, are up to date on their vaccinations with the increase in cases across Ontario.
What is measles?
Measles is a highly contagious infection caused by the measles virus. It is contagious from 4 days before the rash starts to 4 days after the rash starts. Symptoms of measles can develop 7 to 21 days after exposure to the virus. If you have had contact with someone who has been diagnosed with measles, it is important to monitor for symptoms for 21 days after your last exposure. The measles virus lives in the nose and throat of a person who is infected and can be spread through the air (from breathing, coughing, or sneezing). The measles virus can live in the air or on surfaces for up to 2 hours.
Severe complications, while rare, include respiratory failure, encephalitis (swelling of the brain), and death. People at greatest risk for complications related to measles are unvaccinated infants, unvaccinated pregnant people, and people who are immunocompromised. Around 9 out of 10 people who are not fully protected against measles will become infected following close contact with a person who is infected with measles.
Current Situation
On March 6, 2025, The Chief Public Health Officer of Canada released a statement indicating an ongoing increase in the number of measles cases in Canada and strongly urging all Canadians to ensure they are vaccinated against measles. While the initial source of these outbreaks was related to travel, the majority of people with recent infections were exposed in their communities. Most are unvaccinated or under vaccinated, and many have required hospitalization.
Public Health Ontario reports on the number of measles cases in Ontario. With increasing cases across Ontario, The Chief Medical Officer of Health in Ontario released a statement on March 14, 2025 about the current state of measles in the province, including recommendations that Ontarians should ensure themselves, and their children, are up to date on their vaccinations.
Vaccination is the most effective way to prevent measles. Measles vaccines are tested and effective at protecting you and others from serious illness. Measles is a highly contagious, airborne disease that can lead to serious health complications.
The best way you can protect yourself and others against measles is by getting the measles vaccine. This vaccine is combined with the vaccine for mumps and rubella and is known as the MMR vaccine. The MMR vaccine can also be combined with the varicella vaccine (MMR-V) for some populations. MMR and MMR-V are very safe vaccines and very effective against measles. Two doses of measles vaccination is 99% effective at preventing infection.
If you are travelling consult a health care provider at least six weeks before you travel to review your immunization history and make sure you are up to date with your vaccines.
What should I do if I was exposed to someone with measles?
Depending on the situation, your vaccination history, and other risk factors, a public health official may advise you of the need to stay home from work or school, get tested, get preventive treatment or get vaccinated.
What should I do if I have symptoms of measles?
If you develop symptoms of measles, you should be assessed by a physician, and notify the health care facility that you plan to visit so that they are aware of your symptoms prior to your arrival. You should also wear a medical grade mask to the appointment. In the meantime, stay at home to avoid potentially exposing other people (“home isolation”). Measles is diagnosed by a blood test, a urine sample and a nasopharyngeal swab.
If you are having a medical emergency, call 911 or visit the nearest emergency department. Advise them of your symptoms, if you were exposed to measles and if possible wear a medical grade mask.
What is Ottawa Public Health’s role?
Ottawa Public Health (OPH) follows up with all people who are suspected of or diagnosed with measles and their contacts. If there are cases in Ottawa, OPH will work with health system partners, workplaces, and school boards to limit the spread of the virus. OPH also offers routine immunization services for children and youth who live in Ottawa and who are facing barriers in getting their routine immunizations in the community.
More information is available on the Ottawa Public Health website:
