Demand for measles vaccines has increased in Ottawa as an historically large measles outbreak continues to spread in Ontario.
Dr. Trevor Arnason, acting medical officer of health for Ottawa Public Health, said this week that OPH administered 1,500 measles-containing vaccines in the first three months of 2025 alone, compared to 3,900 in 2024.
There have been no cases of highly infectious disease reported in Ottawa, but Arnason told Ottawa’s Board of Health that health officials continue to monitor the situation closely. There have been 816 measles cases reported in the province since the ongoing outbreak began in October, a number that is likely to increase when Public Health Ontario publishes an update later this week. The majority of those affected are unimmunized children.
Cases were initially concentrated in southwestern Ontario but have since spread to 15 public health units in the province, including the one next door to OPH, which includes Kingston, Belleville and surrounding areas.
Arnason noted that routine childhood vaccines were traditionally administered by family physicians. The province-wide shortage of primary care providers has been one factor in the province’s dropping immunization levels. Gaps and delays related to the pandemic, as well as vaccine hesitancy fueled by misinformation, have also been contributors to gaps in vaccination levels.
Measles was declared eliminated in Canada in 1998 due to the success of immunization and timely surveillance. The current outbreak in Ontario is the largest one since then.
Measles, which can cause serious illness or even death, is preventable through vaccination. It is so infectious that up to 18 susceptible people can be exposed by one infected person. The infection can remain in the air two hours after an infected person has left a room.
When immunization rates are high — 95 per cent or more — it is unlikely any cases imported from countries where measles continues to spread would infect many people.
Surveillance in Ottawa includes meticulously checking vaccination records of students who are required to have nine vaccinations — or an exemption — in order to attend school.
During the 2024-25 school year, public health officials in Ottawa have checked immunization records of seven and 17 year olds, sending notifications to the families of those whose immunizations are not up to date.
As a result of those efforts, Arnason said the number of seven year olds missing one or more vaccination has dropped from 70 per cent at the beginning of the year to 24 per cent. The number of 17 year olds missing one or more required vaccine has dropped from 59 per cent to 34 per cent. Arnason said he expects those numbers to drop further. OPH has not suspended any students, but that could come eventually.
Both OPH and partners such as Kids Come First have been stepping up to make it easier for people to update their vaccines, said Arnason.
“Although we have more work to do to continue to promote immunization uptake, our efforts are making a difference.”
