How Ottawa has (so far) avoided a measles outbreak

Ottawa has so far been spared from the largest measles outbreak in 30 years, which has affected other areas of the province and the country. 

There's likely a straightforward reason for that, according to Dr. Trevor Arnason, interim head of Ottawa Public Health.

"We have had historically strong rates of vaccination in Ottawa that has protected us from cases," he said. "Vaccination is the only plausible explanation for why you don't have spread in an area."

Arnason said that's especially welcome news after the city's vaccination rate dipped during COVID.

"The pandemic disruptions actually did cause people to not receive vaccines, which is a concern, and we are updating people's vaccines right now," he said.

Between last October and last Thursday, 350 confirmed or probable measles cases were recorded in Ontario, the majority within the jurisdiction of Southwestern Public Health, which includes Oxford County, Elgin County and the City of St. Thomas. 

Hastings County in eastern Ontario had recorded 35 measles cases as of Wednesday afternoon, all involving unvaccinated patients.

The last reported measles case in Ottawa was in 2019, with only nine cases reported in the five years before that.

Health authority says to check children's vaccine status, amid rising measles cases

4 days ago

Duration 2:01

Vancouver Coastal Health is reminding parents to check their children's vaccine status. It comes with measles on the rise globally and outbreaks in Ontario and Texas. As Michelle Ghoussoub reports public health officials are warning vaccination rates in B.C. are worryingly low.

Catching up from pandemic

Arnason said while there's no guarantee, a vaccination rate of 95 per cent is usually sufficient to prevent the spread of measles within a community. Anything less — even 90 per cent — leaves the door open.

"We cannot become complacent because we're seeing more importation," Arnason said. "Ultimately, we need to increase our measles vaccination rates coming out of the [COVID-19] pandemic."

One of the greatest challenges facing Ontario and other provinces is knowing who's vaccinated and who's not, especially among young pre-schoolers.

The vaccination rate for 17-year-olds is more than 90 per cent, but among children under the age of six, Arnason said it's still uncertain what the rate is for those with measles, mumps and rubella (MMR). 

He said outreach programs and vaccination clinics run by CHEO, the city's children's hospital, have aided those efforts.

"What percentage of one year olds are vaccinated? We won't know until five years later when they go to school, and that's the gap — and even then, that data is self-reported," said Dr. Kumanan Wilson, CEO and chief scientific officer at Ottawa's Bruyère Health Research Institute and an internal medicine physician at The Ottawa Hospital.

Wilson pointed to the general increase in measles across the Americas and Europe.

"One of the major concerns is people aren't vaccinated, and that may be a legacy of the pandemic that people didn't have access to primary care," he said.

Health Canada suggests children should get two doses of the MMR vaccine, the first between the ages of one year and 15 months, and a second between the ages of four and six.

Arnason suggests people who don't know their vaccination status visit OttawaPublicHealth.ca/Measles or their primary care provider. CHEO's Kids Come First clinic and neighbourhood health and wellness hubs are also options.