Need an expert? Measles: what is the situation in Canada?

Posted on Tuesday, May 28, 2019

A doctor preparing to give a vaccine

We sat down with Dr. Ann Jolly, Professor at uOttawa's School of Epidemiology and Public Health, to get some context on measles and the situation in Canada. She is available to speak to members of the media on this subject: ajolly@uottawa.ca

In the last few weeks, numerous new measles cases have been confirmed all across Canada, notably in Montreal, Toronto, and Saint John. Our neighbours to the South have been grappling with their worst measles outbreak in 25 years, and many fear that with the alarming rate at which new case are discovered north of the 49th parallel, Canada might be next.

Measles is a highly contagious and dangerous disease that many doctors never thought would make such a comeback, especially in a developed country like Canada. According to experts, Canadians should stay alert even if the outbreak situation is not yet critical.

“We actually have good vaccination rates due to hard work by public health staff and also due to our publicly funded health-care system, but we can and must do better,” explained Dr. Ann Jolly, associate professor at the University of Ottawa’s School of Epidemiology and Public Health.

“Herd immunity”: Canada needs higher vaccination rates

“Herd immunity” refers to the fact that once a critical proportion of people have been vaccinated, their sheer number make it very unlikely that the few who are unvaccinated will ever be exposed to a specific virus – in this case, measles.

The vaccination rates necessary to create “herd immunity” are higher than 95%. When this level of vaccination is reached, the “herd”, or majority, provides “immunity” from infection to the minority.

“Measles is one of the most infectious pathogens we know, in that it results in the highest number of secondary infected contacts for each infected case,” explained Dr. Jolly. “So all babies under one year, and people whose immune system is compromised, who cannot get the vaccine, or in whom it is ineffective, need to be protected by the 95% or 97% of us who are properly vaccinated.”

According to 2013 figures produced by the Public Health Agency of Canada, the estimated vaccination coverage for measles in Canada is around 85.7%. These numbers are good, but they are clearly not as good as they should be.

Anti-vaxx propaganda is to blame

Many factors explain the decreasing rates of vaccination and the growing distrust of vaccines in Canada over the last few years. The main reason, according to Dr. Jolly, is the circulation of anti-vaccine beliefs and the spread of misinformation through social media.

“In an attempt to search for information on vaccines, my search engine started suggesting ‘information’ and ‘scientific’ sites where I could get ‘unbiased’ information,” explained Dr. Jolly. “Over half of those sites were ‘anti-vaxx’ websites encouraging parents to find the vaccine ‘facts’ that would protect their children. This is really worrying and damaging to Canada’s public health.”

Ironically, the measles vaccine’s success over the years may also have played a part in the current situation.

“The fact that many people have not seen a child with measles for a long time due to the vaccines’ effectiveness allows them to forget what a nasty infection this is,” added Dr. Jolly. “Not only have people forgotten how serious this disease can be, the vaccine has been so effective that even some physicians, who haven’t dealt with measles often – if at all, are having difficulty recognizing emerging cases.”

Members of the media may directly contact the following expert(s):

Dr. Ann Jolly

Dr. Ann Jolly
Associate professor
ajolly@uottawa.ca

For more information:
Orian Labrèche
Media Relations Officer
Cell: 613-863-7221
orian.labreche@uottawa.ca

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