Federal Health Minister Mark Holland says he is "deeply concerned" about the emergence of measles outbreaks in Canada, a risk that experts say has grown as infections grow internationally and the country continues to struggle to meet vaccination targets.

"Frankly, we're seeing a lot of illness that was almost rendered non-existent starting to come back because of vaccine hesitancy," he said in a press conference Monday.

"We have to de-politicize health information. We have to be a society that follows science and evaluation."

Described as among the most infectious diseases known to humankind, measles can spread through contact and droplets in the air, and may cause a variety of symptoms ranging from fever, cough and a rash to, in rare and extreme cases, complications with pregnancy and life-threatening inflammation of the brain.

In recent years, measles outbreaks have increased dramatically outside Canada, with one recent World Health Organization (WHO) report tracking notable outbreaks in 37 different countries and an 18 per cent rise in estimated infections between 2021 and 2022 globally. In that time, there was a 43 per cent increase in estimated measles-related deaths.

In Canada, meanwhile, the disease remains rare, with weekly case reports from the Public Health Agency of Canada (PHAC) routinely showing case counts in the single digits or fewer. Between the outset of the COVID-19 pandemic and the beginning of this year, PHAC data show just 16 total federally reported measles infections.

Recently, concerns have circulated that Canada hasn't seen the last of the disease, which once appeared in the tens of thousands of cases annually, but dropped drastically in the decades following the advent of a vaccine for the virus in the 1960s.

Noting the disease's extreme transmissibility, PHAC's standing target for measles vaccinations is 95 per cent for a first dose by each Canadian's second birthday. A report from the agency published last year shows that only an estimated 92 per cent of Canadian two-year-olds had received at least one dose as of 2021, leaving potential gaps in effective herd immunity.

The problem has been made worse in recent years by the COVID-19 pandemic, which health experts note disrupted regular immunization protocols internationally.

A report from the WHO and U.S. Centers for Disease Control and Prevention (CDC) found that millions children worldwide missed a scheduled vaccination in 2022 alone. A separate University of Toronto study, meanwhile, found that the early months of the pandemic saw a 1.7 per cent drop in coverage for the measles-mumps-rubella vaccine among a sample of Ontario children under two, nearing the two to five per cent decreases the study said are associated with exponential growth in the size of measles outbreaks.

"Interventions for providers and parents are needed to ensure adequate catch-up of delayed/missed immunizations to prevent potential outbreaks," the study concluded.

This year, there have been scattered case reports of measles in Ontario, B.C. and Saskatchewan. In Quebec, public health officials this week warned residents to catch up on their vaccinations as the number of detected cases reached about 10, located mainly in Montreal.

"It can go up very, very fast," Quebec public health director Luc Boileau said in a press conference Monday.

Holland also underscored the importance of immunization to fight and protect against the diseases of the past.

"There was a debate around vaccines, and this was frustrating – I know it was for a lot of health-care workers – talking to folks who'd say 'well, you know, I don't see measles, mumps, rubella, I don't see these things, so, you know, we don't really need a vaccine,'" Holland said.

"[They were] not understanding the reason we don't have them is because we have a vaccine."