With nearly 200 cases confirmed and a new health care setting exposure, the top doctor of the health unit at the epicentre of Ontario's measles outbreak continues to urge vaccination as the best defence against the highly infectious disease.
Ninh Tran, medical officer of health at Southwestern Public Health, said on Friday 195 cases have been confirmed in Elgin and Oxford counties since October 2024. The number of cases has increased by nearly 60 since March 6.
The actual number of cases is likely higher because some haven't been identified, he said.
Southwestern Public Health advised the public on Thursday of another measles exposure that occurred on March 11 between 7:09 a.m. and 9:30 a.m. at Woodstock Hospital.
The majority of people who’ve contracted measles are unvaccinated, Tran said on Friday. Vaccines offer the best protection against the disease, he said.
“(Cases) are predominantly in individuals who are not up to date in vaccinations, and particularly who have never been immunized against measles, and that's still the biggest risk,” Tran said. “We have a safe and effective vaccine that's up to 99 per cent effective if you've had two doses.”
Tran said 133 of the region's 195 cases are in individuals younger than 18. “Serious complications in children who have measles” had been reported, he has said previously. Some patients have experienced difficulty breathing, extreme dehydration, increased heart rates, diarrhea, vomiting and high fever, Tran said.
While Southwestern Public Health continues to see a spike in measles cases, one of neighbouring health units has seen few cases while another deals with a growing number of cases.
Middlesex-London Health Unit has reported one case. The person was “likely exposed while visiting a neighbouring jurisdiction,” the health unit said on Monday.
Alex Summers, medical officer of health for the Middlesex-London, said on Friday the health unit is closely monitoring the measles outbreak in Southwestern Ontario.
Summers credits a high vaccination rate in London and Middlesex County for the lack of cases.
“Our estimates for the 2023-2024 school year were that 90 per cent of seven-year-olds were up to date with their measles vaccine, and nearly 95 per cent of 17-year-olds were up to date for their measles vaccine.
The numbers place Middlesex-London above the provincial average, Summers said.
Citing data from Public Health Ontario's immunization data tool, Middlesex-London Health Unit said 70 per cent of seven-year-olds in the province were fully vaccinated against measles in 2023-24 while the rate for 17-year-olds was 91 per cent.
Though the Middlesex-London Health Unit has managed to dodge an outbreak thus far, Grand Erie Public Health – the health unit for Haldimand, Norfolk and Brant County and Brantford – has continued to see cases rise.
As of Friday, Grand Erie Public Health said there were 110 measles cases, 91 of which were confirmed and 19 probable cases since October. Of the confirmed cases, 70 are children while 21 are adults.
Public Health Ontario reported Thursday there are now 350 cases in the outbreak that began on Oct. 28, 2024.
The number of cases reported in Ontario over the past five months is about three and a half times what the province saw in the decade between 2013 and 2023.
“It is unusual to see this kind of spread," said Dr. Christine Navarro, a public health physician at Public Health Ontario. "It’s not something that we’ve experienced in the province in many, many years, certainly not since elimination of measles in Canada in 1998."
Measles symptoms include a red rash, fever, cough, runny nose, upper respiratory-type symptoms, red eyes and fatigue. Serious complications such as pneumonia, encephalitis, blindness and death are possible. People most at risk of measles complications include pregnant women, young children and the immunocompromised.