Ontario’s Chief Medical Officer of Health is recommending families in western Ontario, including in Grey-Bruce, seek earlier measles vaccination for babies and children under five as the area continues to record cases of the airborne virus.

The Ontario Ministry of Health has expanded the eligibility criteria for the measles vaccine based on the increased risk of measles exposure in western Ontario.

While Ontario’s publicly funded vaccine schedule recommends children receive a first dose of a measles-containing vaccine at one year of age and a second dose between ages four and six, the Ministry of Health now recommends the following for children who reside in or visit areas, such as Grey-Bruce, with higher measles exposure risk:

• Infants (age 6-11 months): Should receive one dose of the measles, mumps, rubella (MMR) vaccine. These children will still have to receive two additional doses of the vaccine after they turn one year of age.
• Children (age 1-4 years): Children who have received their first dose of the MMR vaccine are encouraged to receive a second dose as soon as possible (at a minimum of four weeks from the first dose).

In addition, the Ministry of Health recommends that all adults (age 18 and up) born on or after 1970 ensure they have received a second dose of a measles-containing vaccine.

The risk of acquiring measles in Grey-Bruce remains very low for people who are fully immunized and those considered immune to the virus, specifically those born in or before 1970.

However, the virus does spread easily between individuals who have not been immunized or are not immune.

One dose of a measles-containing vaccine is about 85% to 95% effective at preventing measles. With two doses, efficacy rises to nearly 100%.

Forty confirmed or probable measles cases have been reported in Grey-Bruce since a multi-jurisdictional measles outbreak began in Ontario in October 2024. Thirty-two of the cases were reported in 2025.

Nearly all of the local cases were unvaccinated.

Grey Bruce Public Health has created a dedicated measles webpage, available at the following link: Measles – Grey-Bruce. This webpage includes information on measles-containing vaccines, including when individuals should be vaccinated, along with a list of local measles exposure locations, and additional information on the measles virus, including symptoms and the virus’s infectious period.