Ontario measles case count tops 800, 155 new infections since last week

Ontario is reporting 155 new measles cases over the last week, pushing the province's case count to 816 since an outbreak began in the fall.

The number of new cases has increased again after a few weeks of appearing to stabilize in the 100-per-week range, which public health physicians had taken as a sign of potential optimism.

Public Health Ontario says there have now been 61 hospitalizations — that's 11 more than last week — including 47 children. Unimmunized kids are the predominant group infected by the outbreak.

Most cases are still in Ontario's southwestern public health unit, but they spread to two more public health units this week, including Hamilton and Northeastern, which covers Timmins and Englehart.

Dr. Susy Hota, division head for infectious diseases at the University Health Network, told CBC News she never thought she would see this many measles cases in Ontario. 

"I haven't seen numbers like that in my career, so it's it's very disturbing to see that," she said.

Hota says lower vaccination rates could be to blame for the outbreak. 

"It was always a background worry that vaccine-preventable diseases like measles could come back and have a resurgence if the vaccination levels were low enough," she said. "It's just unfortunate that we haven't had a chance to try and help catch up and get that message out to people before it really hit our population more locally."

Over 90 per cent of people who don't have protection through vaccination or previous infection will likely be infected if exposed to the virus, she said — and that's why people should find out if they're immune or not.

"If you know that you haven't been fully vaccinated, this is a time to get it done. You really want to try and get ahead of this before you end up in a situation where you may be exposed," she said.

Dr. Ninh Tran, medical officer of health at Southwestern Public Health, says there's been a 130 per cent increase in measles vaccinations at local public health clinics from January to April compared to last year.

That translates to an additional 940 doses in arms.

Tran also spoke about schools beginning to issue suspensions this week to some of the thousands of students who aren't fully vaccinated, and the urgent calls for the province to digitize its immunization record system.

Physicians have been calling on the province to create a central digital vaccine registry for over a decade with the spread of measles shining light on the outdated yellow immunization cards.