Measles cases in Ontario between January 2013 and January 2025 as per Public Health Ontario.
Public health authorities are grappling with a rapidly growing measles outbreak in southwestern Ontario, with 19 confirmed cases as of January 29. The outbreak, initially thought to be confined to a small group, has now escalated, prompting officials to sound the alarm over its fast-paced spread.
Cases Surge Across Multiple Regions
The outbreak is primarily affecting two public health jurisdictions: Southwestern Public Health, which covers Oxford County, Elgin County, and the City of St. Thomas, has reported three cases, all in children. Meanwhile, Grand Erie Public Health, responsible for Brantford, Brant County, Haldimand County, and Norfolk County, has recorded 16 infections—13 in children and three in adults.
Dr. Malcolm Lock, acting medical officer of health for Grand Erie Public Health, explained how the situation has evolved from an isolated cluster to a full-fledged outbreak. "We were initially seeing a few cases in a non-immunized group, but with the numbers rising so quickly, we now classify this as an outbreak—and we expect the numbers to keep climbing," he warned.
The Challenge of an Under-Vaccinated Population
Health officials have linked the outbreak to a specific community with low vaccination rates, making it difficult to track and contain the virus.
“This particular population does not support vaccination, which complicates our ability to assess the number of unvaccinated individuals at risk,” Dr. Lock noted. "Many of the affected children attend private schools that may not fully cooperate with public health investigations, citing privacy concerns."
Without complete vaccination records, officials face hurdles in identifying potential contacts of infected individuals, especially in school settings. In response, Grand Erie Public Health has been actively sharing information with local schools, churches, and parents about measles prevention and the importance of vaccination.
Measles on the Rise Across Ontario
Ontario has seen an increase in measles cases, with 65 reported between January 2024 and January 2025, according to Public Health Ontario. This includes 39 confirmed and 26 probable cases spread across 11 public health units.
The latest data from the province’s integrated Public Health Information System, updated on January 15, shows a concerning trend. Grand Erie Public Health had reported five cases at that time, while Southwestern Public Health had recorded 26. The province has also seen eight hospitalizations and one death due to measles.
Experts attribute this resurgence to declining vaccination rates and a global uptick in measles cases.
The Importance of Vaccination
Dr. Ninh Tran, medical officer of health for Southwestern Public Health, emphasized the effectiveness of the measles vaccine. “It’s incredibly safe and provides strong protection,” he said, adding that widespread immunization is the best defense against the disease.
Dr. Lock echoed this sentiment, stressing that herd immunity plays a crucial role in protecting vulnerable populations. “When people choose not to get vaccinated, they’re increasing the risk for others—especially children,” he warned.
He also pointed out that due to the success of past vaccination efforts, many younger generations have never witnessed the severity of measles complications. “Because they haven’t seen the disease firsthand, they may underestimate the risks. But serious complications, though rare, can have lifelong consequences.”
Public Health Officials Face an Uphill Battle
With vaccination rates declining, public health experts fear more outbreaks could emerge in the future—not just for measles but for other preventable diseases like polio.
“We have a lot of work to do,” admitted Dr. Lock. “The messages from anti-vaccine groups are spreading more widely than ours. Public health needs to improve our outreach and understand why younger populations are hesitant about vaccines. If we don’t, we’re going to see a rise in preventable illnesses.”
Possible Exposure Locations Identified
Grand Erie Public Health has released a list of places where the public may have been exposed to measles, including schools, restaurants, and medical centers. The latest exposure sites include:
- Bethel Baptist School (Simcoe) – Jan. 20-21 (8 a.m. – 5 p.m.)
- Grey Gretzky Medical Centre (Brantford) – Jan. 22 (10:45 a.m. – 2:45 p.m.)
- Walsingham Christian School (Walsingham) – Jan. 21-23 (8 a.m. – 5 p.m.)
Recognizing Measles Symptoms
Measles symptoms usually appear between 7 and 21 days after exposure. The early signs resemble a common cold, with fever, cough, runny nose, and watery red eyes. A distinctive rash—starting on the face before spreading to the rest of the body—typically follows.
What makes measles particularly dangerous is its airborne transmission. The virus can linger in the air for up to two hours after an infected person has left, making it extremely easy to catch. Individuals are contagious for four days before and after the rash appears.
What To Do If Exposed
Anyone who suspects they may have been exposed to measles should avoid public spaces, especially hospitals, doctors’ offices, and childcare centers, to prevent further spread.
Public health officials strongly recommend getting two doses of the MMR vaccine (Measles, Mumps, and Rubella), which offers near-complete immunity. “Even one dose provides about 85% protection,” Dr. Lock stated, “but with two doses, immunity is close to 100%.”
As the outbreak continues, health officials urge the public to remain vigilant and prioritize vaccination to curb the spread of this highly contagious disease.
