35 new measles cases reported south of London in past week

Southwestern Public Health (SWPH) says measles in its jurisdiction have grown to take up most of the province's outbreak, with 35 new cases reported in the past seven days.

The total number of cases reported in the the area covering Elgin and Oxford Counties, as well as the City of St. Thomas, is now 343 since October 2024 - almost half of the province's total of 692 as of April 9. 

Thirty-five of those cases have required hospitalization at some point, said medical officer of health Dr. Ninh Tran, and more than 90 per cent have been in someone who has not been immunized. 

"My message today is for parents and guardians in our region," Tran said during a media briefing Thursday. "If you have children attending school or childcare, it is important to know what to expect if there was a measles exposure in one of these settings." 

The health unit is required to investigate possible exposures after receiving a positive measles test result, he said. While steps are taken to tell the public they may have been exposed, there's no guarantee the health unit can reach everyone. 

"The people who've had two doses of measles-containing vaccine are generally not at risk from that exposure as well," Tran added. "Those born before 1970 are generally not at risk. Under-immunized or unimmunized individuals are at risk from that exposure." 

The majority of cases reported to SWPH — more than 73 per cent — continue to be in people under the age of 18. The numbers are part of the largest measles outbreak Canada has seen in more than a decade. 

A memo from Ontario's chief medical officer of health Dr. Kieran Moore in March confirmed that the current outbreak was from a "large gathering with guests from Mennonite communities in New Brunswick last fall."

There has been an uptick in vaccinations across all ages, said Tran. They are up 130 per cent between January 1st and April 8th compared to the same period last year. 

Tran is also urging parents to update their child's vaccination records after getting immunized. It save a lot of time and effort for the health unit if a vaccine registry was digitized, he added. 

"Either people can't seem to find them, so they have to contact their healthcare provider and then report to us," he said. 

"[A digital registry] would save a lot of additional time and energy for parents, for healthcare providers and as far as ourselves and it would really help guide our response. That would be incredible." 

Most people in the province still track their shots on paper, which the Ontario Immunization Advisory Committee is encouraging the Ministry of Health to change. 

The committee said in a position statement that it "strongly urges" the province to develop an electronic immunization registry, which would replace the current method of keeping track of shots on yellow paper.