The Medical Officer of Health in Huron Perth said vaccine hesitancy is a growing issue and is helping to spread measles.
Dr. Miriam Klassen revealed that the rate of unvaccinated people has increased.
"They were declining prior to COVID. We were seeing increased vaccine hesitancy," Klassen explained. "And during COVID, as you know, so many health care resources were redeployed to the COVID response. Vaccination was put on pause, and so many people fell behind in their vaccination schedules."
Klassen added that although vaccination rates are still strong, it's no longer enough to keep the highly contagious disease at bay. She said about 90 per cent of students were vaccinated in a recent school survey.
"There are people who are un or under-immunized, some due to medical reasons, some due to religious or reasons of conscience," she pointed out. "Measles, now that it's been introduced, is finding those people. So 86 per cent of cases in Ontario have been unimmunized."
She stated the numbers are similar in Huron Perth. She said if immunity in a population falls below 95 per cent, measles will spread among those who are not immune. Canada eliminated measles in 1998, other than small pockets related to travel.
She said measles is extremely infectious and can spread easily. Nine out of ten people who are not immune will develop an infection after even a seemingly short exposure. Cases are infectious from four days before the onset of a rash until 21 days after exposure. Susceptible contacts are potentially infectious from five days after exposure to 21 days after exposure.
However, Klassen added that misinformation also circulates rapidly.
"One of the challenges we face is the spread of mis and disinformation, which has always been there, but now with social media, like there's so much more mis and disinformation out there. It's very easy to spread using those channels," she continued.
Klassen stressed that the publicly funded measles immunization strategy has a long history of being safe and effective. She said that fully immunized people are not likely to get measles. If they do develop measles anyway, the case is mild and less transmissible.
She added that immunization is the best way to gain immunity, as measles has some serious consequences.
"Pneumonia, brain swelling, hospitalization in about 10 per cent of cases, and sadly, death in about two out of 1,000 cases," she explained. "As well as a severe, rare, fatal, sort of progressive neuro cognitive complication that occurs many years after infection, called Subacute sclerosing panencephalitis. It's rare, but it's always fatal."
There have been 55 confirmed and probable cases in Huron Perth since February 27, with five Huron Perth residents hospitalized with measles. In Ontario, 42 of the 43 hospitalized cases involved people who are unimmunized.
Meanwhile, one new measles case surfaced in Grey Bruce a week ago, and the region had reported eight cases last October, which were also related to the outbreak. The bulk of cases in Ontario are located in the Southwestern (Elgin and Oxford County) and Grand Erie (Haldimand, Norfolk, Brant counties) public health regions. Ontario is part of a multi-jurisdictional measles outbreak with measles activity occurring in Ontario, New Brunswick, and Manitoba
Measles usually begins with a fever, cough, runny nose, and red, watery eyes, followed by a red, blotchy rash that starts on the face and spreads to the body and limbs.