A measles outbreak is currently hitting Quebec and babies under the age of one are among the most vulnerable as they are not vaccinated. The Quebec Immunization Committee (CIQ), however, advises the Ministry of Health not to increase the age of vaccination since this risks compromising collective immunity.
There is currently community transmission of measles in Quebec, one of the most contagious diseases in the world. Serious complications of this disease include encephalitis, pneumonia and in one in 3000 cases, death.
According to the most recent data from the provincial government, as of April 24, there have been 50 confirmed cases of measles since the start of 2024.
Vaccination is the best way to protect against measles since there is no cure, only treatments depending on the complication developed.
According to the Quebec vaccination schedule, children are vaccinated against measles at the ages of 12 and 18 months and they are 95% protected from this disease throughout their life.
Since a first case of community transmission was confirmed in Quebec, public health has been concerned about a low vaccination rate in certain regions. It launched a targeted vaccination campaign to try to increase these rates.
The proportion of individuals who need to be protected against measles in order to eliminate community transmission is estimated at approximately 95%.
In this context, many parents are worried about their unvaccinated baby under one year old. The National Institute of Public Health of Quebec (INSPQ) confirms in a notice that the Info-Santé service has received calls from parents who wish to bring forward the vaccination of their 10-month-old child.
The Ministry of Health has been asked by the regions to provide guidance on this issue. He mandated the CIQ to assess the risks and send him a recommendation.
The CIQ said the data suggests that “the long-term effectiveness of two doses of vaccine is lower when the first dose is given before 12 months of age.”
It concludes that even with very high vaccination coverage, loss of vaccine effectiveness can compromise the ability to control measles transmission at the population level.
In addition, no study demonstrates whether two doses administered after the age of 12 months would compensate for the loss of effectiveness of the first early dose.
For these reasons, the CIQ advises the government not to bring forward the first dose of vaccine before the age of one.
In its recommendation to the Ministry of Health and Social Services, the CIQ underlines that France maintains the age of the first dose at one year “despite transmission considered endemic and a higher incidence of cases than in Quebec”. The United Kingdom, which recently declared a state of emergency in connection with a resurgence of measles, is also not bringing forward the first dose for infants.
The CIQ, however, notes an exception: the Netherlands, which authorized vaccination among 6 to 14 month olds in communities where vaccination coverage was less than 90% during a measles outbreak in 2013-2014. Antibodies in children who received an early dose were significantly lower than those who received a first dose at 14 months.
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reference: www.lapresse.ca