Health officials in Ontario are ramping up efforts to control a significant measles outbreak that has seen a surge in cases across the province. As of April 8, 2025, Public Health Ontario reported 89 new measles cases since March 26, bringing the total number of confirmed and probable cases this year to 655. This alarming rise in cases has been linked to a travel-related incident in New Brunswick.
The Southwestern Public Health region, which includes communities such as St. Thomas and Woodstock, has reported 43 new cases—the largest increase in the province during the most recent reporting period. Dr. Ninh Tran, the medical officer of health for the region, emphasized the importance of vaccination in combating the outbreak. "Measles is one of the most contagious illnesses globally, and currently the most effective way to safely prevent measles is through vaccination," he stated.
Dr. Tran's team is focusing on vaccinating individuals who are at risk of contracting the disease. This primarily includes those who have never had measles or have not received the vaccine, as well as those who have only received one dose. Public health officials stress that two doses of the measles vaccine are necessary for effective prevention.
Unlike other vaccines, such as those for flu or COVID-19, which primarily lessen the severity of infection, the measles vaccine is designed to prevent infection altogether. "Two doses of measles-containing vaccine prevents the infection altogether," Dr. Tran explained.
In response to the outbreak, vaccination clinics have been established in various locations, including a recent clinic held above a hockey arena in Caledonia, where families were encouraged to get their children vaccinated. Rachel Vaarkamp brought her five-year-old son, Tyse, to receive the measles shot. "We don’t have a family doctor right now and realized that it was time to get his vaccinations, especially with the recent cases in the area," she said.
The situation has drawn attention beyond Ontario, with public health officials in New York issuing a travel advisory to residents ahead of the spring break. The New York State Department of Health warned that measles is highly contagious and can easily cross borders. "Measles is only a car ride away!" they cautioned, noting that around 90% of people exposed to the virus will become infected if they are not vaccinated.
This outbreak is particularly concerning given the historical context. Canada’s measles outbreak began in October 2024, following a travel-related case in New Brunswick that sparked additional cases in Ontario. Since the beginning of 2025, a total of 655 measles cases have been reported in Ontario, with 560 confirmed and 95 probable cases. This is a stark contrast to the previous decade, which saw just 101 confirmed cases between 2013 and 2023, and only 64 cases recorded in 2024 alone.
As the outbreak continues to spread, health officials are emphasizing the importance of vaccination. The measles-mumps-rubella (MMR) vaccine is a live attenuated vaccine that contains a weakened version of the virus, generating strong, lifelong immunity without causing serious disease in individuals with healthy immune systems. A single dose of the vaccine is estimated to be 85 to 95 percent effective, while a second dose boosts protection to nearly 100 percent.
Despite these efforts, there is growing concern about vaccine hesitancy in recent years, which has contributed to the current outbreak. The NDP Health critic has noted that the province must engage family physicians to understand the barriers to vaccination that their patients face. Years of underfunding in public health have resulted in many children falling behind on their vaccinations, and there is a pressing need to support family doctors and nurses in ramping up vaccination efforts.
The situation is not isolated to Ontario. Other parts of North America are also experiencing rising measles cases. Public health officials in the District of Temiskaming recently reported two new cases, although they stated that the risk to the public remains low as the situation is being monitored closely.
As the spring and summer travel season approaches, public health officials are urging anyone who is not vaccinated to seek protection before traveling. The New York State Department of Health has highlighted the risks associated with travel during this outbreak, reminding residents that measles can spread quickly in areas with low vaccination rates.
Measles is one of the most contagious infectious diseases, more so than COVID-19, influenza, or chickenpox. This high level of contagiousness can lead to rapid outbreaks, particularly in communities where vaccination rates are low. The best way to protect oneself against measles is through vaccination, and public health officials are working tirelessly to ensure that those who are susceptible are given the opportunity to receive the vaccine.
As Ontario grapples with this public health crisis, the focus remains on communication and vaccination as the primary tools for controlling the outbreak. Health officials are hopeful that increased awareness and access to vaccination will help curb the spread of this highly contagious disease.
In conclusion, the measles outbreak in Ontario serves as a stark reminder of the importance of vaccination and public health measures in preventing the spread of infectious diseases. With ongoing efforts to increase vaccination rates and combat vaccine hesitancy, health officials are committed to protecting the health of the community and preventing further outbreaks.
