LONDON, June 20, 2025
Measles cases are surging in Ontario, with non-vaccinated individuals disproportionately affected.
- Over 2,000 cases have been officially identified in Ontario since October 18, 2024.
- The vast majority of infected children and adolescents were not vaccinated.
- The province has reported measles-related deaths for the first time in decades.
What’s happening with measles in Ontario? The Ontario public health department has reported a total of 2,083 measles cases between October 18, 2024, and June 10. The data paints a stark picture of how the disease is impacting the population.
According to a recent report, non-vaccinated individuals are overrepresented in the case numbers. In addition to 75% of all identified cases being children or adolescents, “almost all children, infants and adolescents” infected (96%) were unvaccinated, along with 68% of adults.
Before 1982, when Alberta began systematically offering the measles-rubella vaccine to children, the number of annual cases surpassed 4,000 on three occasions in the 1970s and six times in the 1960s.
A Deadly Resurgence
For the first time since the outbreak began, an infant died from measles in Ontario at the beginning of June. Her mother was infected during pregnancy. In May 2024, a child under five died following a measles infection; this was the first death since 1989, according to the Ministry of Health.
As of February, with “only” 140 cases, Ontario had already surpassed the total number of cases (101) identified throughout the previous decade (2013-2023).
Underestimated Numbers
Doctors in Ontario and Alberta warn that the official figures may be underestimated, similar to the situation in Texas. Many parents might not seek medical attention for their children if symptoms are mild, which allows the virus to spread within families and undervaccinated communities.
STAT, an American medical magazine, wrote in March that Texas doctors noticed that measles patients arrived at the hospital extremely ill, suggesting that some people delayed seeking treatment until the disease became severe.
Measles is exceptionally contagious: a single infected person can, in theory, infect 18 others, compared to the flu’s 2. In numerous cases, measles can lead to respiratory complications like pneumonia or neurological complications such as encephalitis. The World Health Organization estimates the risk of death at between 1 and 3 per 1,000 cases.
