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Influenza vaccine coverage for children aged six to 23 months very low in Ontario


Despite a universal influenza immunization program in Ontario, only 4.7 per cent of children aged six to 23 months were fully immunized by physicians for the 2008/09 influenza season, one of the lowest levels since the introduction of universal immunization according to research from the Institute for Clinical Evaluative Sciences (ICES) published today in Pediatrics.

“Universal influenza immunization was introduced in Ontario in 2000, but coverage rates are very low for young children considered at high risk for complications of influenza infection. Medically high-risk children, including low birth weight babies, are somewhat more likely to be immunized than healthy children; however, overall coverage (the number who are immunized) seems to be more related to parental attitudes to vaccine, as reflected by maternal immunization, than medical risk factors,” says Dr. Astrid Guttmann, senior author and senior scientist with ICES and a pediatrician at The Hospital for Sick Children (SickKids).

The population-based, retrospective cohort study found: 

  • Influenza vaccine coverage among children aged 6-23 months in Ontario is very low (4.7 per cent fully immunized for the 2008/09 influenza season), despite a universal influenza immunization program, high primary care visit rates, and recommendation from immunization advisory committees.
  • Children aged six to 23 months with chronic conditions, or who were born at a low birth weight, are more likely to be immunized, although immunization among these children is still quite low (less than 10 per cent fully immunized in both groups.)
  • Mothers who choose to get immunized against influenza themselves and live in neighbourhoods with higher incomes are more likely to have their children immunized.
  • Children with a pediatrician as their primary care provider are more likely to be immunized.
  • Coverage is higher in younger children from other Canadian provinces and the US even though those jurisdictions did not have universal influenza immunization at that time.

“With many Canadian provinces and the US implementing universal influenza immunization, more research is needed to determine barriers to effective vaccine promotion and delivery for young children. Strategies to increase coverage in this age group should target not only children, but also their physicians and families, as multiple characteristics from these levels predict influenza immunization,” says Michael Campitelli, lead author of the study and epidemiologist at ICES.

Authors: Michael A. Campitelli, Miho Inoue, Andrew J. Calzavara, Jeffrey C. Kwong, Astrid Guttmann.

The study “Low rates of physician-administered influenza immunization in young children under Ontario’s Universal Influenza Immunization Program,” is in the latest issue of Pediatrics.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.



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