Quebec has seen its number of measles cases stabilize in recent days. The key to this success: the gradual improvement of our vaccination coverage, which is still far from the ideal targets to limit the spread. But we should not declare victory too quickly either, underlines an expert, because nothing prevents a new outbreak from taking place in the coming weeks. Especially since the number of Quebec cases already exceeds all Canadian cases in 2023.
As of Tuesday, March 26, Quebec Public Health recorded 28 cases of measles, including 16 in Montreal. Data from the Ministry of Health and Social Services (MSSS), transmitted by email to Duty, show that the province confirmed the reporting of nine cases between February 4 and March 2, eight more between March 3 and 9, and eleven between March 10 and 23. Quebec therefore does not seem to have experienced any additional cases since last week.
“It is not an exponential increase in cases, probably thanks to the interventions that have been made,” explains the DD Caroline Quach-Thanh, pediatrician and microbiologist-infectious disease specialist at CHU Sainte-Justine.
At the CHU Sainte-Justine emergency room, children under 12 months of age were also vaccinated following exposure to the disease. Usually, the first dose of measles vaccine is given on the child’s first birthday. Vaccination campaigns have also been deployed in the Montreal region, where the majority of cases have been recorded.
A cover far from the hoped-for target
In a press conference held at the beginning of the month, the regional public health director of the metropolis, DD Mylène Drouin, for her part, emphasized that certain schools had a vaccination rate well below the target of 95%. Vaccination coverage there sometimes fell to 30%, she confirmed.
“We would like to be at 95%, because that is really the threshold from which transmission is less plausible,” underlines the DD Quach-Thanh. ” That being said, [à Montréal], there have been many cases in children under 12 months, who are too young to be vaccinated, because there was an outbreak in a pediatric emergency room. » The situation would have been completely different if the outbreak had taken place, for example, among vaccinated adults, she adds.
In Canada, only the provinces of Newfoundland and Labrador (97%) and Prince Edward Island (98%) have reached the ideal threshold among two-year-olds, according to data from the National survey on childhood vaccination coverage (ENCVE). In Quebec, vaccination coverage reached 93.2% as of 2021.
Observing the same data among seven-year-old children, the country recorded vaccination coverage of 79.2% in 2021, a drop compared to 2017 (87%). This is also the first time since 2013 where this threshold has fallen below 80%. In Quebec, MSSS data for the 2021-2022 school year report vaccination coverage of 88% among primary school students, and 92% in secondary school.
Impact of the pandemic
Last week, the national director of public health, Luc Boileau, was particularly concerned about “vaccine fatigue” which has taken hold in Quebec since the start of the COVID-19 pandemic.
In its survey, Federal Public Health asked participants whether the COVID-19 pandemic had changed their attitude toward vaccinating their children. The majority (79.7%) say the pandemic had no influence on their decision; only a small proportion (2.5%) say they feel less inclined to do so.
The pandemic, however, has had an impact on the vaccination schedule for some. “There was, at times, greater difficulty in obtaining an appointment to vaccinate our children, particularly at the start of the pandemic,” notes the DD Quach-Thanh.
ENCVE data show in particular that the vaccination rate for measles, at 79.8%, is lower among two-year-old children whose vaccination had to be delayed by more than 30 days due to the pandemic, compared to children who saw no delay affect their vaccination schedule (95.7%).
Stay on guard
To see the number of confirmed cases stagnating for several days is “excellent news”, argues the DD Quach-Thanh. However, we must not declare victory too quickly. “For the moment, the fire has not caught. We must continue to improve our vaccination coverage, so that we are not completely exposed when there is the next case. Because there will be a next case,” she insists.
Several outbreaks are taking place across the planet, and nothing is stopping the virus from finding its way back to Quebec in the weeks to come. The pediatrician notably raises the example of Chicago, which has seen 33 confirmed cases of measles since the start of the year, despite the fact that the city is among the best protected against the disease in the United States.
As of March 21, American public health has recorded 64 cases of measles on its national territory. This is already more than the total number of cases recorded in 2023, i.e. 58 cases. We see the same thing in Quebec: the number of cases recorded in the province, at present, has more than doubled compared to that of last year across Canada, which was 12 cases.