Measles may be spreading in some Canadian communities, officials warn

There are early signals that measles - one of the world's most contagious viruses - may be quietly spreading within parts of Canada as health officials brace for more imported infections during the March Break travel season.

The country now has at least nine confirmed infec‐ tions for 2024, according to a CBC News count, a twomonth tally that's not far off the dozen cases reported Canada-wide for all of 2023.

Two recent cases, identi‐ fied in Quebec and Ontario, were not tied to prior travel and didn't come into contact with any known measles cases, suggesting the individ‐ uals may have been infected within their communities.

Laval Public Health an‐ nounced on Thursday that one infected person has been isolating at home since Feb. 26 - and previously vis‐ ited a school, a corner store, a medical clinic and CHU Sainte-Justine Hospital, all in the Montreal suburb of Laval, while highly contagious. The individual was unvaccinated and hadn't traveled, officials said.

That infection is one of three known cases in Que‐ bec, the province's public health director Dr. Luc Boileau said on Friday, as several more suspected in‐ fections remained under in‐ vestigation by late afternoon.

"We think it is the begin‐ ning of transmission inside the community," warned Boileau.

Quebec's case comes on the heels of another infection reported this week in York Region, a municipality north of Toronto, which was not linked to travel. There, health officials say a man in his 30s got infected from an un‐ known source.

"The unique thing about this case - a rather unfortu‐ nate thing - is that this case does not have any travel his‐ tory or any history of expo‐ sure," said Dr. Barry Pakes, medical officer of health for York Region, in an interview with CBC News.

The man was vaccinated and had a mild course of ill‐ ness, and it's possible he may have caught the virus in the community, Pakes said. Prior to being diagnosed, the indi‐ vidual spent time in various parts of the Greater Toronto Area, including a restaurant in Mississauga, a hospital in Vaughan, and a medical clinic in Woodbridge.

Pakes said the man's vac‐ cination status likely lessens the risk that he transmitted the virus any further, but where he caught it remains a mystery - a situation the physician described as "con‐ cerning" but expected.

"It doesn't mean there is an outbreak by any means," he added, "because we have great vaccination rates, thankfully."

Another recent case, an unvaccinated child in Brant County, Ont., was hospital‐ ized after acquiring measles on a trip to Europe, and more than 200 people may have been exposed at various set‐ tings including Pearson Inter‐ national Airport near Toronto - though health officials told local media that no further infections have been re‐ ported.

No risk of 'massive measles outbreak'

Multiple medical experts who spoke to CBC News agreed that any onward spread of measles in Canada will likely fizzle out. Still, outbreaks re‐ main a possibility if infections strike communities where vaccination uptake is lower.

"We've had the importa‐ tion of measles in Canada and had small chains of transmission within the country … but by no means in March of 2024 are we at risk for a massive measles outbreak in Canada," said Dr. Isaac Bogoch, an infectious diseases specialist with the University Health Network in Toronto.

"Coverage rates are still high enough that we should be able to prevent significant amounts of onward trans‐ mission," echoed Dr. Jesse Papenberg, a pediatric infec‐ tious diseases specialist at the Montreal Children's Hos‐ pital.

Still, he added, there can be pockets where vaccine coverage rates aren't high enough to stop secondary spread when there is an im‐ ported case.

Country-wide data also shows overall vaccination rates have dropped, while a new survey suggests more Canadian parents are wary of getting their children routine shots - despite long standing medical consensus that vac‐ cines are both effective and safe.

WATCH | Measles infec‐ tions exploding in Europe, prompting fears it could happen here:

Federal data from 2021 shows that 79 per cent of children had two doses of the measles, mumps, and rubella vaccine by their sev‐ enth birthday, down from 83 per cent in 2019 and 87 per cent in 2017. That suggests close to two in 10 children hadn't yet had their full set of shots, far from Canada's target of 95 per cent cover‐ age for that age group.

Meanwhile an opinion poll, released Wednesday by the Angus Reid Institute, found 17 per cent of parents of minors say they are "really against" vaccinating their kids, compared with four per cent in 2019.

"It's very concerning when we hear that people are in‐ creasingly skeptical of vacci‐ nations, especially the rou‐ tine childhood vaccination," Bogoch said.

"If people are choosing not to vaccinate themselves or vaccinate their children, it's going to come to no one's surprise that we see the resurgence of vaccine-pre‐ ventable illnesses, even here in Canada."

Virus is highly conta‐ gious

Those trends could make controlling measles more challenging going forward.

Thought to be one of the most contagious health threats, the virus spreads easily through the air, trans‐ mits before people even show symptoms, and can linger inside enclosed spaces for up to two hours. One in‐ dividual infected by measles can infect nine out of 10 of their unvaccinated close con‐ tacts, notes the World Health Organization.

It also has a long incuba‐ tion period - usually between 10 and 14 days - and, in some cases, can lead to lifethreatening complications, including pneumonia, brain swelling, or death.

Yet health officials stress the two-dose vaccine regimen against measles is more than 95 per cent effec‐ tive at preventing infection, offering a simple path to avoiding the most serious cases.

Dr. Theresa Tam, Canada's chief public health officer, stressed that Canadians should check their vaccina‐ tion records and ensure they're up-to-date on their measles shots. And "if in doubt," she recommended getting an additional dose prior to any travel.

Tam also said she's hope‐ ful the country still has a "firewall" in terms of ade‐ quate vaccination levels.

"I do think it's a bit like a spark dropping into an area that's dry, and you start a bit of a fire," she added. "So areas that are underimmu‐ nized - there are pockets in Canada - and that's where you will see outbreaks. It is a possibility."