Canada's Measles Outbreak: A Threat to Elimination Status

Strategic Insights -

Canada's 30-year streak of almost eliminating measles is under threat due to a growing outbreak of the highly contagious virus. The current outbreak, linked to an international travel-related case in New Brunswick in October 2024, has spread to Ontario and other provinces, resulting in 1,848 reported cases as of last week. This is the largest measles outbreak in Canada since the virus was almost eliminated in 1998. The outbreak has claimed the life of a child under five years old, the first death in over a decade.

Key Takeaways:

  • The current measles outbreak in Canada is the largest since the virus was almost eliminated in 1998, with 1,848 reported cases as of last week, out of a total of 2,515 cases in 2025.
  • The outbreak has spread to Ontario and other provinces, primarily in communities with low immunity to measles, and has become a significant public health concern.
  • The gap in immunization coverage is being blamed on the COVID-19 pandemic, which delayed some routine measles, mumps, rubella, and varicella (MMRV) vaccination schedules for young children, and also caused others to question vaccines in general.
  • Health professionals are warning that if the current chain of transmission continues beyond October 2025, Canada could lose its elimination status, which would be the first time in 30 years.
  • The continued increase in outbreak cases and geographic spread is predominantly due to ongoing exposures and transmission among individuals who have not been immunized.
  • Public Health Ontario recommends that children get two doses of the measles vaccine, with a special catch-up campaign implemented in 1996 to increase immunization coverage.
  • Herd immunity requires about 95% of a population to be vaccinated, and those who are unvaccinated should stay home when ill and seek timely medical care to reduce the risk of ongoing transmission.
  • Health professionals are promoting post-exposure prophylaxis (PEP), which involves giving the vaccine to individuals who have been exposed to measles and are not expected to have measles immunity.
  • The risk of getting measles for Canadians is moderate, but the chance of prolonged transmission over the next six months is moderate-high.

Statistics:

  • 1,848 reported measles cases in Ontario and other provinces as of last week.
  • 2,515 measles cases in Canada in 2025, with fewer than 100 cases considered part of the initial outbreak.
  • The initial outbreak case was reported in New Brunswick on October 18, 2024, with an exposure warning at Toronto Pearson International Airport.
  • 1974-1983: MMR combination vaccine introduced in Canada.
  • 1992: National Consensus Conference recommends eliminating measles in Canada by 2005.
  • 1995: Spike in measles cases in Ontario, with those already vaccinated with one dose getting infected.
  • 1996: Public health agency recommends two doses of measles vaccine, with a special catch-up campaign implemented.
  • 1998: Canada achieves elimination status for measles, with endemic transmission no longer taking place.

Sources:

  • Public Health Ontario
  • Health Canada
  • National Library of Medicine
  • World Health Organization
  • Canada.ca (for more information on measles, treatment, and vaccination options)