Measles prevalence rates are declining in some Montreal schools, raising the risk of outbreaks

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Measles vaccination rates have dropped to 75 percent in some schools in Montreal — a dangerous situation that could lead to possible future outbreaks, a Montreal health department official warned Friday.

The warning came Wednesday as authorities confirmed a new case of measles in an unvaccinated child recently returned from Africa. Public health investigators tracked the boy's contacts at school and elsewhere and tried to contact anyone who had been in close contact with the person during the outbreak between Jan. 26 and Feb. 6.

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Montreal last declared a measles outbreak in May 2019, when officials discovered that at least a few people contracted the measles in the city rather than abroad.

The World Health Organization saw a 30-fold increase in measles cases in Europe last year, including 21,000 hospitalizations and five measles-related deaths, amid “a backlog in vaccination coverage from 2020 to 2022.” Meanwhile, the US Centers for Disease Control issued an emergency alert on January 25, advising the public to be vigilant after 23 cases were confirmed in several states between December 1 and January 23.

The U.S. cases include “seven direct measles imports from international travelers and two outbreaks of more than five cases each. Most of these cases occurred among children and adolescents who did not receive the measles vaccine … even if they were age-eligible,” the CDC said.

Dr. Paul Le Guerrier, head of the Montreal Department of Public Health's immunization team, noted that community measles vaccine coverage must be at least 95 percent to prevent local transmission of the highly contagious virus. He estimated vaccination rates in Montreal are between 80 and 88 percent, but coverage is now as low as 75 percent in some schools.

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“The problem we're seeing is the reporting of outbreaks, whether it's in the States, Europe, Africa and Asia,” Le Guerrier said. “Because there are many outbreaks abroad and many Canadians travel, unprotected Canadians are at high risk of being infected while traveling and returning with the disease and then spreading it to people in Montreal who are not properly protected.”

In addition to the red spots and rashes of measles, the disease can cause serious complications in children and adults. According to the CDC, one in five unvaccinated people with measles in the US will be hospitalized. Three out of every 1,000 children infected with measles die from respiratory and neurological complications.

After one year of age, two doses of the measles vaccine are almost 100 percent effective in preventing the disease. There are two types of measles vaccines available in Canada: the measles vaccine and the measles-mumps vaccine. The first dose is usually given to children at 12-15 months of age, and the second dose to children at 18 months or before school.

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But people can get the measles vaccine at a later age, including adults. Le Guerrier advised Canadians who have not been vaccinated against measles to get vaccinated before traveling abroad.

After British gastroenterologist Andrew Wakefield conducted a now-discredited study in 1998 showing a link between the MMR vaccine and autism, measles vaccination rates began to decline worldwide.

Le Guerrier offered other reasons for Montreal's vaccine rejection.

“We have a large ethno-cultural population with different languages, so parents may not understand the importance of vaccination,” he explained. “Or they have a lot of issues to deal with when the school sends the vaccination letter — even if it's translated, and we translate the letters in 12 languages ​​in Montreal — they still don't vaccinate their kids.”

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