The Windsor-Essex County Health Unit (WECHU) has updated its guidance for measle vaccinations as regional cases continue to rise.
Those between six and 12 months old may now be eligible to receive an additional dose of the MMR vaccine (Measles, Mumps and Rubella) based on a risk assessment conducted by healthcare providers.
Dr. Mehdi Aloosh, the health unit’s medical officer of health, advised of the changes during a board meeting on Thursday afternoon.
“The good news is that the risk for the general population in Windsor-Essex County Health Unit is low because we have a good vaccination rate,” Aloosh told reporters after the meeting.
“The bad news is that we will see this is transmitted through people who are unvaccinated, and it will be a long period that we will see the transmission of the disease among those unvaccinated populations.”
Typically, the vaccine is administered once at 12 months old, and a second dose is given years later.
WECHU has confirmed 20 cases of measles, a figure which may be higher due to undiagnosed or misdiagnosed cases.
An increase in transmission in southwestern Ontario and across the province has created the need for babies to receive an additional vaccine.
“This is based off the recent research in Canada, they found that infants after the age of three months, they carry very low immunity from moms,” Aloosh said.
“So, given our circumstances that measles is circulating in our area, we identified the risk for those infants are high, and then they need one dose of MMR vaccine.”
One person with measles has the transmissibility to infect 20 other people if they’re unvaccinated, he noted.
Health Canada estimated a single dose of the measles vaccine has shown efficacy between 85 per cent and 95 per cent.
According to Public Health Ontario, 440 cases of measles have been reported provincially in 2025.
Aloosh noted about 6.6 per cent of patients reported to have measles are under the age of one.
He added previous guidelines for vaccinations are due to vaccines being more effective as the body develops.
“Immune system needs to be developed to the certain level that responds well to a vaccine and produces that antibody and make memory cells,” Aloosh noted.
“Those memory cells remember that exposure with the disease and later on, years and years and decades after that, they remember that exposure, that vaccine as they can protect individuals from the disease.”
The region’s top doctor noted the move aligns WECHU with other health units affected by measles outbreaks.
Symptoms of measles
- fever
- cough
- runny nose
- red, watery eyes
- red blotchy and spotted rashes
For those experiencing measles symptoms, WECHU advises reaching out to a healthcare provider to inform them of symptoms or an exposure so they can prepare.
