Measles vaccinations of toddlers at 89%, below 'herd immunity' level

Statistics Canada on Tuesday released the results of a national survey on childhood immunizations showing a high percentage of two-year-olds have been vaccinated against a variety of childhood diseases, though the figure is still short of so-called herd immunity.

About 89 per cent of two-year-olds had received the recommended number of immunizations against measles, mumps and rubella, according to the 2013 Childhood National Immunization Coverage Study sponsored by the Public Health Agency of Canada (PHAC).

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Doctors say a 95 per cent vaccination rate for measles is ideally needed for "herd immunity" in the population to prevent outbreaks.

Herd immunity occurs when enough individuals in a given population have immunity through vaccination or previous exposure, which confers protection to those who aren't immunized by preventing a contagious bacteria or virus from setting up a chain of infection.

Measles cases were reported this year in Manitoba, Ontario and Quebec.

"While there have been outbreaks of measles recently largely among unimmunized populations, the fact that measles has not spread to the general population in Canada illustrates that measles vaccine uptake is very good," Sylwia Krzyszton, senior adviser of media relations for the public health agency, said in an email response to CBC News.

Other results regarding immunizations for two-year-olds:

• Diphtheria - 77.4%
• Whooping cough - 77.0%
• Tetanus 77.0%
• Polio 91.1%
• Haemophilus influenza type B - 72.7%
• Measles - 89.6%
• Mumps - 89.2%
• Rubella - 89.2%
• Chicken pox - 73.1%
• Meningococcal infection - 88.6%
• Pneumococcal infection - 79.3%

The survey was intended to determine whether children at ages two, seven and 17 are being immunized in accordance with recommended immunization schedules for publicly funded vaccines.

Information about immunizations was collected from the parent or guardian, and, in about a third of the children, immunization records came from their health-care provider.

The initial press release from Stats Canada on Tuesday did not include any historical or regional data, although PHAC was expected to release more information regarding the survey soon.

In most cases the totals fell short of immunization coverage goals set by Canada several years ago.

"Overall, Canada has high vaccination coverage rates, but there are still some unimmunized and under-immunized people, which can result in the spread of vaccine-preventable diseases," said Krzyszton. "The results underscore the need for continued attention to issues such as vaccine hesitancy and under-immunization."

She added that the low levels of vaccine-preventable diseases in Canada demonstrate the immunization effort here is laudable.

Canada was heavily criticized in a 2013 UNICEF report for an overall rate of immunization coverage that fell under 90 per cent, although many in the Canadian medical community questioned the report's methodology.

Based on answers from parents and caregivers, 1.5 per cent of children had not received any kind of immunization. In the 2011 version of the survey, one per cent of caregivers reported that their child had never received any of the routine immunizations.

Parents of children who had received at least one immunization responded positively at a rate between 95 and 97 per cent to questions about the importance, safety and effectiveness of vaccines for children.

While there's been a large amount of media coverage of parents who have moderate or strong objections to the vaccination schedule for small children, a recent report from the C.D. Howe Institute on immunization suggested that access to a physician, poverty and length of time in Canada were more likely explanations for why a child would not be fully vaccinated according to schedule. Complacency and procrastination were also cited as potential causes.

Data was also collected in the 2013 survey on immunization against the human papilloma virus for girls aged 12 to 14 and 17. The HPV vaccination rate was 72 per cent for girls 12 to 14, and 64 per cent for 17-year-old girls. When measured in 2011, HPV vaccine coverage was estimated at 43 per cent for 17-year-old girls.